diff --git a/lib/codegen/fromcto/graphql/graphqlvisitor.js b/lib/codegen/fromcto/graphql/graphqlvisitor.js
index bb0f2323..a8100b3c 100644
--- a/lib/codegen/fromcto/graphql/graphqlvisitor.js
+++ b/lib/codegen/fromcto/graphql/graphqlvisitor.js
@@ -15,6 +15,7 @@
 'use strict';
 
 const util = require('util');
+const { ModelUtil } = require('@accordproject/concerto-core');
 
 /**
 * Convert the contents of a ModelManager to GraphQL types, based on
@@ -52,7 +53,7 @@ class GraphQLVisitor {
         } else if (thing.isField?.()) {
             return this.visitField(thing, parameters);
         } else if (thing.isMapDeclaration?.()) {
-            return;
+            return this.visitMapDeclaration(thing, parameters);
         } else if (thing.isRelationship?.()) {
             return this.visitRelationship(thing, parameters);
         } else if (thing.isEnumValue?.()) {
@@ -171,6 +172,28 @@ class GraphQLVisitor {
         return null;
     }
 
+    /**
+    * Visitor design pattern
+    * @param {MapDeclaration} mapDeclaration - the object being visited
+    * @param {Object} parameters  - the parameter
+    * @return {Object} the result of visiting or null
+    * @private
+    */
+    visitMapDeclaration(mapDeclaration, parameters) {
+        const keyType = mapDeclaration.getKey().getType();
+        const valueType = mapDeclaration.getValue().getType();
+
+        let key = ModelUtil.isPrimitiveType(keyType) ? this.toGraphQLType(keyType) : keyType;
+        let value = ModelUtil.isPrimitiveType(valueType) ? this.toGraphQLType(valueType) : valueType;
+
+        parameters.fileWriter.writeLine(0, `type ${mapDeclaration.getName()} {`);
+        parameters.fileWriter.writeLine(1, `key: ${key}`);
+        parameters.fileWriter.writeLine(1, `value: ${value}`);
+        parameters.fileWriter.writeLine(0, '}');
+
+        return null;
+    }
+
     /**
     * Visitor design pattern
     * @param {Relationship} relationship - the object being visited
diff --git a/test/codegen/__snapshots__/codegen.js.snap b/test/codegen/__snapshots__/codegen.js.snap
index b031ca12..08e15db8 100644
--- a/test/codegen/__snapshots__/codegen.js.snap
+++ b/test/codegen/__snapshots__/codegen.js.snap
@@ -632,6 +632,30 @@ type Address {
    dictionary5: Map5!
    dictionary6: Map6!
 }
+type Map1 {
+   key: String
+   value: String
+}
+type Map2 {
+   key: String
+   value: DateTime
+}
+type Map3 {
+   key: String
+   value: SSN
+}
+type Map4 {
+   key: String
+   value: Concept
+}
+type Map5 {
+   key: SSN
+   value: String
+}
+type Map6 {
+   key: SSN
+   value: Employee
+}
 type Company {
    name: String!
    headquarters: Address!
@@ -5758,6 +5782,30 @@ type Address {
    dictionary5: Map5!
    dictionary6: Map6!
 }
+type Map1 {
+   key: String
+   value: String
+}
+type Map2 {
+   key: String
+   value: DateTime
+}
+type Map3 {
+   key: String
+   value: SSN
+}
+type Map4 {
+   key: String
+   value: Concept
+}
+type Map5 {
+   key: SSN
+   value: String
+}
+type Map6 {
+   key: SSN
+   value: Employee
+}
 type Company {
    name: String!
    headquarters: Address!
diff --git a/test/codegen/fromcto/graphql/graphqlvisitor.js b/test/codegen/fromcto/graphql/graphqlvisitor.js
index 1bf7db3a..a944000a 100644
--- a/test/codegen/fromcto/graphql/graphqlvisitor.js
+++ b/test/codegen/fromcto/graphql/graphqlvisitor.js
@@ -23,10 +23,14 @@ const GraphQLVisitor = require('../../../../lib/codegen/fromcto/graphql/graphqlv
 const ModelFile = require('@accordproject/concerto-core').ModelFile;
 const ModelManager = require('@accordproject/concerto-core').ModelManager;
 const ClassDeclaration = require('@accordproject/concerto-core').ClassDeclaration;
+const MapDeclaration = require('@accordproject/concerto-core').MapDeclaration;
 const EnumValueDeclaration = require('@accordproject/concerto-core').EnumValueDeclaration;
 const Field = require('@accordproject/concerto-core').Field;
 const RelationshipDeclaration = require('@accordproject/concerto-core').RelationshipDeclaration;
 const FileWriter = require('@accordproject/concerto-util').FileWriter;
+const { ModelUtil } = require('@accordproject/concerto-core');
+
+let sandbox = sinon.createSandbox();
 
 const MODEL_WITH_DECORATORS = `
 namespace test
@@ -339,6 +343,37 @@ describe('GraphQLVisitor', function () {
         });
     });
 
+    describe('visitMapDeclaration', () => {
+        it('should write a type for a Map', () => {
+            let param = {
+                fileWriter: mockFileWriter
+            };
+
+            sandbox.stub(ModelUtil, 'isPrimitiveType').callsFake(() => {
+                return true;
+            });
+
+            const mockMapDeclaration    = sinon.createStubInstance(MapDeclaration);
+            const getKeyType            = sinon.stub();
+            const getValueType          = sinon.stub();
+
+            getKeyType.returns('String');
+            getValueType.returns('String');
+            mockMapDeclaration.getName.returns('map1');
+            mockMapDeclaration.getKey.returns({ getType: getKeyType });
+            mockMapDeclaration.getValue.returns({ getType: getValueType });
+
+            graphQLVisitor.visitMapDeclaration(mockMapDeclaration, param);
+
+            param.fileWriter.writeLine.withArgs(0, 'type map1 {').calledOnce.should.be.ok;
+            param.fileWriter.writeLine.withArgs(1, 'key: String').calledOnce.should.be.ok;
+            param.fileWriter.writeLine.withArgs(1, 'value: String').calledOnce.should.be.ok;
+            param.fileWriter.writeLine.withArgs(0, '}').calledOnce.should.be.ok;
+
+            sandbox.restore();
+        });
+    });
+
     describe('visitRelationship', () => {
         it('should write a line for a relationship', () => {
             let param = {