diff --git a/README.markdown b/README.markdown
index 7461e41..21d7002 100644
--- a/README.markdown
+++ b/README.markdown
@@ -142,6 +142,10 @@ if init
 end
 ```
 
+You can set any additional properties like custom webhook URLs in the json payload by passing `additional_options: <your options>`.
+See the API documentation for all available options [here](https://api-reference.datatrans.ch/). 
+
+
 Start a transaction
 -------------------
 
diff --git a/lib/datatrans/json/transaction/init.rb b/lib/datatrans/json/transaction/init.rb
index b9810bb..0bb354f 100644
--- a/lib/datatrans/json/transaction/init.rb
+++ b/lib/datatrans/json/transaction/init.rb
@@ -41,6 +41,7 @@ def request_body
       }
 
       body["option"] = params[:option] if params[:option].present?
+      body.deep_merge!(params[:additional_options]) if params[:additional_options].present?
 
       body
     end
diff --git a/spec/json/init_spec.rb b/spec/json/init_spec.rb
index f74fa4c..38bd073 100644
--- a/spec/json/init_spec.rb
+++ b/spec/json/init_spec.rb
@@ -81,6 +81,36 @@
     end
   end
 
+  context "with additional_options specified" do
+    it "uses additional_options in request_body" do
+      params_with_option = @valid_params.merge(additional_options:         {webhook: {
+        url: "https://datatrans-test-webhook.ch/webhook"
+      }})
+      request = Datatrans::JSON::Transaction::Init.new(@datatrans, params_with_option)
+
+      expected_request_body_with_options = @expected_request_body.merge(webhook: {url:
+                                                                                   "https://datatrans-test-webhook.ch/webhook"})
+      expect(request.request_body).to eq(expected_request_body_with_options)
+    end
+  end
+
+  context "with additional_options with redirect specified" do
+    it "uses additional_options in request_body" do
+      params_with_option = @valid_params.merge(additional_options:         {redirect: {
+        method: "POST"
+      }})
+      request = Datatrans::JSON::Transaction::Init.new(@datatrans, params_with_option)
+
+      expected_request_body_with_options = @expected_request_body.merge(redirect: {
+        successUrl: "https://pay.sandbox.datatrans.com/upp/merchant/successPage.jsp",
+        cancelUrl: "https://pay.sandbox.datatrans.com/upp/merchant/cancelPage.jsp",
+        errorUrl: "https://pay.sandbox.datatrans.com/upp/merchant/errorPage.jsp",
+        method: "POST"
+      })
+      expect(request.request_body).to eq(expected_request_body_with_options)
+    end
+  end
+
   context "failed response" do
     before do
       allow_any_instance_of(Datatrans::JSON::Transaction::Init).to receive(:process).and_return(@failed_response)
diff --git a/spec/json/transaction_spec.rb b/spec/json/transaction_spec.rb
index 486b12e..5b6be30 100644
--- a/spec/json/transaction_spec.rb
+++ b/spec/json/transaction_spec.rb
@@ -1,7 +1,7 @@
 require "spec_helper"
 
 describe Datatrans::JSON::Transaction do
-  it "returns correct trasaction_path" do
+  it "returns correct transaction_path" do
     params = {transaction_id: "230223022302230223"}
     transaction = Datatrans::JSON::Transaction.new(@datatrans, params)