diff --git a/packages/functions/src/serializer.ts b/packages/functions/src/serializer.ts
index 677d22d8804..f3e8f7c6719 100644
--- a/packages/functions/src/serializer.ts
+++ b/packages/functions/src/serializer.ts
@@ -51,6 +51,9 @@ export class Serializer {
     if (data === true || data === false) {
       return data;
     }
+    if (data instanceof Date) {
+      return data.toISOString();
+    }
     if (Object.prototype.toString.call(data) === '[object String]') {
       return data;
     }
@@ -95,6 +98,14 @@ export class Serializer {
     if (typeof json === 'function' || typeof json === 'object') {
       return mapValues(json!, x => this.decode(x));
     }
+    if (
+      typeof json === 'string' &&
+      /^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(.[0-9]+)?(Z)?$/.test(
+        json
+      )
+    ) {
+      return new Date(json);
+    }
     // Anything else is safe to return.
     return json;
   }
diff --git a/packages/functions/test/serializer.test.ts b/packages/functions/test/serializer.test.ts
index 3de6d6d0d9c..f4bb4d44c69 100644
--- a/packages/functions/test/serializer.test.ts
+++ b/packages/functions/test/serializer.test.ts
@@ -80,6 +80,18 @@ describe('Serializer', () => {
     expect(serializer.decode(1.2)).to.equal(1.2);
   });
 
+  it('encodes date', () => {
+    expect(serializer.encode(new Date('2021-02-10T13:26:37.977Z'))).to.equal(
+      '2021-02-10T13:26:37.977Z'
+    );
+  });
+
+  it('decodes date', () => {
+    expect(serializer.decode('2021-02-10T13:26:37.977Z')).to.deep.equal(
+      new Date('2021-02-10T13:26:37.977Z')
+    );
+  });
+
   it('encodes string', () => {
     expect(serializer.encode('hello')).to.equal('hello');
   });