diff --git a/BACKLOG.md b/BACKLOG.md
index abe8eab..1cf6e4e 100755
--- a/BACKLOG.md
+++ b/BACKLOG.md
@@ -8,6 +8,7 @@
 
 ### Medium Priority
 
+- [ ] feat: Promotion code on ticket
 - [ ] feat: Promoter system with event creation, ticket types creation and metrics display
 - [ ] feat: Multiple ticket types (early bird, VIP, general admission)
 - [ ] feat: Refund management system
@@ -53,6 +54,7 @@
 
 ## 🚧 Doing
 
+- [ ] feat: Promotion code on ticket
 - [ ] feat: Page to display all tickets for an event
 - [ ] feat: Add a link into notification email to order page that display all tickets
 
diff --git a/app/controllers/orders_controller.rb b/app/controllers/orders_controller.rb
index 9456dd9..f6a6e29 100644
--- a/app/controllers/orders_controller.rb
+++ b/app/controllers/orders_controller.rb
@@ -126,6 +126,20 @@ class OrdersController < ApplicationController
     @total_amount = @order.total_amount_cents
     @expiring_soon = @order.expiring_soon?
 
+    # Handle promotion code application
+    if params[:promotion_code].present?
+      promotion_code = PromotionCode.valid.find_by(code: params[:promotion_code].upcase)
+      if promotion_code
+        # Apply the promotion code to the order
+        @order.promotion_codes << promotion_code
+        @order.calculate_total!
+        @total_amount = @order.total_amount_cents
+        flash.now[:notice] = "Code promotionnel appliqué: #{promotion_code.code}"
+      else
+        flash.now[:alert] = "Code promotionnel invalide"
+      end
+    end
+
     # For free orders, automatically mark as paid and redirect to success
     if @order.free?
       @order.mark_as_paid!
diff --git a/app/models/order.rb b/app/models/order.rb
index 3c84bc7..bc7ff56 100644
--- a/app/models/order.rb
+++ b/app/models/order.rb
@@ -7,6 +7,8 @@ class Order < ApplicationRecord
   belongs_to :user
   belongs_to :event
   has_many :tickets, dependent: :destroy
+  has_many :order_promotion_codes, dependent: :destroy
+  has_many :promotion_codes, through: :order_promotion_codes
 
   # === Validations ===
   validates :user_id, presence: true
diff --git a/app/models/order_promotion_code.rb b/app/models/order_promotion_code.rb
new file mode 100644
index 0000000..9effdee
--- /dev/null
+++ b/app/models/order_promotion_code.rb
@@ -0,0 +1,26 @@
+class OrderPromotionCode < ApplicationRecord
+  # Associations
+  belongs_to :order
+  belongs_to :promotion_code
+
+  # Validations
+  validates :order, presence: true
+  validates :promotion_code, presence: true
+
+  # Callbacks
+  after_create :apply_discount
+  after_create :increment_promotion_code_uses
+
+  private
+
+  def apply_discount
+    # Apply the discount to the order
+    discount_amount = promotion_code.discount_amount_cents
+    order.update!(total_amount_cents: [ order.total_amount_cents - discount_amount, 0 ].max)
+  end
+
+  def increment_promotion_code_uses
+    # Increment the uses count on the promotion code
+    promotion_code.increment!(:uses_count)
+  end
+end
diff --git a/app/models/promotion_code.rb b/app/models/promotion_code.rb
new file mode 100644
index 0000000..4eb56fc
--- /dev/null
+++ b/app/models/promotion_code.rb
@@ -0,0 +1,23 @@
+class PromotionCode < ApplicationRecord
+  # Validations
+  validates :code, presence: true, uniqueness: true
+  validates :discount_amount_cents, numericality: { greater_than_or_equal_to: 0 }
+
+  # Scopes
+  scope :active, -> { where(active: true) }
+  scope :expired, -> { where("expires_at < ? OR active = ?", Time.current, false) }
+  scope :valid, -> { active.where("expires_at > ? OR expires_at IS NULL", Time.current) }
+
+  # Callbacks
+  before_create :increment_uses_count
+
+  # Associations
+  has_many :order_promotion_codes
+  has_many :orders, through: :order_promotion_codes
+
+  private
+
+  def increment_uses_count
+    self.uses_count ||= 0
+  end
+end
diff --git a/app/views/orders/checkout.html.erb b/app/views/orders/checkout.html.erb
index 73fd9c8..bdedda7 100644
--- a/app/views/orders/checkout.html.erb
+++ b/app/views/orders/checkout.html.erb
@@ -118,6 +118,16 @@
           <p class="text-sm text-gray-600">Procédez au paiement pour finaliser votre commande</p>
         </div>
 
+        <!-- Promotion Code Section -->
+        <%= form_tag checkout_order_path(@order), method: :get, class: "mb-6" do %>
+          <div class="flex items-center bg-gray-50 border border-gray-200 rounded-lg p-3">
+            <%= text_field_tag :promotion_code, params[:promotion_code], class: "flex-1 border-none bg-transparent focus:ring-0 text-sm", placeholder: "Code promotionnel (optionnel)" %>
+            <%= button_tag type: "submit", class: "ml-2 btn btn-secondary py-2 px-4 text-sm" do %>
+              Appliquer
+            <% end %>
+          </div>
+        <% end %>
+
         <% if @checkout_session.present? %>
           <!-- Stripe Checkout -->
           <div class="space-y-6">
@@ -131,13 +141,13 @@
               </div>
             </div>
 
-  <button
-    id="checkout-button"
-    data-order-id="<%= @order.id %>"
-    data-increment-url="/api/v1/orders/<%= @order.id %>/increment_payment_attempt"
-    data-session-id="<%= @checkout_session.id if @checkout_session.present? %>"
-    class="w-full btn btn-primary py-4 px-6 rounded-xl transition-all duration-200 transform hover:scale-105 active:scale-95 shadow-lg hover:shadow-xl"
-  >
+<button
+  id="checkout-button"
+  data-order-id="<%= @order.id %>"
+  data-increment-url="/api/v1/orders/<%= @order.id %>/increment_payment_attempt"
+  data-session-id="<%= @checkout_session.id if @checkout_session.present? %>"
+  class="w-full btn btn-primary py-4 px-6 rounded-xl transition-all duration-200 transform hover:scale-105 active:scale-95 shadow-lg hover:shadow-xl"
+>
               <div class="flex items-center justify-center">
                 <i data-lucide="credit-card" class="w-5 h-5 mr-2"></i>
                 Payer <%= @order.total_amount_euros %>€
@@ -194,16 +204,16 @@
 
                 try {
                   // Increment payment attempt counter
-  const orderId = checkoutButton.dataset.orderId;
-  const incrementUrl = checkoutButton.dataset.incrementUrl;
-  console.log('Incrementing payment attempt for order:', orderId);
-  const response = await fetch(incrementUrl, {
-    method: 'PATCH',
-    headers: {
-      'Content-Type': 'application/json',
-      'X-CSRF-Token': document.querySelector('[name=csrf-token]').content
-    }
-  });
+const orderId = checkoutButton.dataset.orderId;
+const incrementUrl = checkoutButton.dataset.incrementUrl;
+console.log('Incrementing payment attempt for order:', orderId);
+const response = await fetch(incrementUrl, {
+  method: 'PATCH',
+  headers: {
+    'Content-Type': 'application/json',
+    'X-CSRF-Token': document.querySelector('[name=csrf-token]').content
+  }
+});
 
                   if (!response.ok) {
                     console.error('Payment attempt increment failed:', response.status, response.statusText);
@@ -224,11 +234,11 @@
                   `;
 
                   // Redirect to Stripe
-  const sessionId = checkoutButton.dataset.sessionId;
-  console.log('Redirecting to Stripe with session ID:', sessionId);
-  const stripeResult = await stripe.redirectToCheckout({
-    sessionId: sessionId
-  });
+const sessionId = checkoutButton.dataset.sessionId;
+console.log('Redirecting to Stripe with session ID:', sessionId);
+const stripeResult = await stripe.redirectToCheckout({
+  sessionId: sessionId
+});
 
                   if (stripeResult.error) {
                     throw new Error(stripeResult.error.message);
diff --git a/db/migrate/20250928180837_create_promotion_codes.rb b/db/migrate/20250928180837_create_promotion_codes.rb
new file mode 100644
index 0000000..e5ae43f
--- /dev/null
+++ b/db/migrate/20250928180837_create_promotion_codes.rb
@@ -0,0 +1,16 @@
+class CreatePromotionCodes < ActiveRecord::Migration[8.0]
+  def change
+    create_table :promotion_codes do |t|
+      t.string :code, null: false, unique: true
+      t.integer :discount_amount_cents, null: false, default: 0
+      t.datetime :expires_at
+      t.boolean :active, default: true, null: false
+      t.integer :usage_limit, default: nil
+      t.integer :uses_count, default: 0, null: false
+      t.datetime :created_at, null: false
+      t.datetime :updated_at, null: false
+    end
+
+    add_index :promotion_codes, :code, unique: true
+  end
+end
diff --git a/db/migrate/20250928181311_create_order_promotion_codes.rb b/db/migrate/20250928181311_create_order_promotion_codes.rb
new file mode 100644
index 0000000..e7d3d23
--- /dev/null
+++ b/db/migrate/20250928181311_create_order_promotion_codes.rb
@@ -0,0 +1,10 @@
+class CreateOrderPromotionCodes < ActiveRecord::Migration[8.0]
+  def change
+    create_table :order_promotion_codes do |t|
+      t.references :order, null: false, foreign_key: true
+      t.references :promotion_code, null: false, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end
diff --git a/test/controllers/orders_controller_promotion_test.rb b/test/controllers/orders_controller_promotion_test.rb
new file mode 100644
index 0000000..348f78c
--- /dev/null
+++ b/test/controllers/orders_controller_promotion_test.rb
@@ -0,0 +1,66 @@
+require "test_helper"
+
+class OrdersControllerPromotionTest < ActionDispatch::IntegrationTest
+  include Devise::Test::IntegrationHelpers
+
+  # Setup test data
+  def setup
+    @user = users(:one)
+    @event = events(:one)
+    @order = orders(:one)
+    sign_in @user
+  end
+
+  # Test applying a valid promotion code
+  def test_apply_valid_promotion_code
+    promotion_code = PromotionCode.create(
+      code: "TESTDISCOUNT",
+      discount_amount_cents: 1000, # €10.00
+      expires_at: 1.month.from_now,
+      active: true
+    )
+
+    get checkout_order_path(@order), params: { promotion_code: "TESTDISCOUNT" }
+    assert_response :success
+    assert_not_nil flash[:notice]
+    assert_match /Code promotionnel appliqué: TESTDISCOUNT/, flash[:notice]
+  end
+
+  # Test applying an invalid promotion code
+  def test_apply_invalid_promotion_code
+    get checkout_order_path(@order), params: { promotion_code: "INVALIDCODE" }
+    assert_response :success
+    assert_not_nil flash[:alert]
+    assert_equal "Code promotionnel invalide", flash[:alert]
+  end
+
+  # Test applying an expired promotion code
+  def test_apply_expired_promotion_code
+    promotion_code = PromotionCode.create(
+      code: "EXPIREDCODE",
+      discount_amount_cents: 1000,
+      expires_at: 1.day.ago,
+      active: true
+    )
+
+    get checkout_order_path(@order), params: { promotion_code: "EXPIREDCODE" }
+    assert_response :success
+    assert_not_nil flash[:alert]
+    assert_equal "Code promotionnel invalide", flash[:alert]
+  end
+
+  # Test applying an inactive promotion code
+  def test_apply_inactive_promotion_code
+    promotion_code = PromotionCode.create(
+      code: "INACTIVECODE",
+      discount_amount_cents: 1000,
+      expires_at: 1.month.from_now,
+      active: false
+    )
+
+    get checkout_order_path(@order), params: { promotion_code: "INACTIVECODE" }
+    assert_response :success
+    assert_not_nil flash[:alert]
+    assert_equal "Code promotionnel invalide", flash[:alert]
+  end
+end
diff --git a/test/models/promotion_code_test.rb b/test/models/promotion_code_test.rb
new file mode 100644
index 0000000..09ca44a
--- /dev/null
+++ b/test/models/promotion_code_test.rb
@@ -0,0 +1,67 @@
+require "test_helper"
+
+class PromotionCodeTest < ActiveSupport::TestCase
+  # Test valid promotion code creation
+  def test_valid_promotion_code
+    promotion_code = PromotionCode.create(
+      code: "DISCOUNT10",
+      discount_amount_cents: 1000, # €10.00
+      expires_at: 1.month.from_now,
+      active: true
+    )
+
+    assert promotion_code.valid?
+    assert_equal "DISCOUNT10", promotion_code.code
+    assert_equal 1000, promotion_code.discount_amount_cents
+    assert promotion_code.active?
+  end
+
+  # Test validation for required fields
+  def test_validation_for_required_fields
+    promotion_code = PromotionCode.new
+    refute promotion_code.valid?
+    assert_not_nil promotion_code.errors[:code]
+  end
+
+  # Test unique code validation
+  def test_unique_code_validation
+    PromotionCode.create(code: "UNIQUE123", discount_amount_cents: 500)
+    duplicate_code = PromotionCode.new(code: "UNIQUE123", discount_amount_cents: 500)
+    refute duplicate_code.valid?
+    assert_not_nil duplicate_code.errors[:code]
+  end
+
+  # Test discount amount validation
+  def test_discount_amount_validation
+    promotion_code = PromotionCode.new(code: "VALID123", discount_amount_cents: -100)
+    refute promotion_code.valid?
+    assert_not_nil promotion_code.errors[:discount_amount_cents]
+  end
+
+  # Test active scope
+  def test_active_scope
+    active_code = PromotionCode.create(code: "ACTIVE123", discount_amount_cents: 500, active: true)
+    inactive_code = PromotionCode.create(code: "INACTIVE123", discount_amount_cents: 500, active: false)
+
+    assert_includes PromotionCode.active, active_code
+    refute_includes PromotionCode.active, inactive_code
+  end
+
+  # Test expired scope
+  def test_expired_scope
+    expired_code = PromotionCode.create(code: "EXPIRED123", discount_amount_cents: 500, expires_at: 1.day.ago)
+    future_code = PromotionCode.create(code: "FUTURE123", discount_amount_cents: 500, expires_at: 1.month.from_now)
+
+    assert_includes PromotionCode.expired, expired_code
+    refute_includes PromotionCode.expired, future_code
+  end
+
+  # Test valid scope
+  def test_valid_scope
+    valid_code = PromotionCode.create(code: "VALID123", discount_amount_cents: 500, active: true, expires_at: 1.month.from_now)
+    invalid_code = PromotionCode.create(code: "INVALID123", discount_amount_cents: 500, active: false, expires_at: 1.day.ago)
+
+    assert_includes PromotionCode.valid, valid_code
+    refute_includes PromotionCode.valid, invalid_code
+  end
+end