diff --git a/openapi_core/schema/schemas/models.py b/openapi_core/schema/schemas/models.py
index cea36d7..6ae4dc9 100644
--- a/openapi_core/schema/schemas/models.py
+++ b/openapi_core/schema/schemas/models.py
@@ -2,13 +2,14 @@
 import attr
 import functools
 import logging
+from base64 import b64decode, b64encode
 from collections import defaultdict
 from datetime import date, datetime
+from uuid import UUID
 import re
 import warnings
 
 from six import iteritems, integer_types, binary_type, text_type
-from uuid import UUID
 
 from openapi_core.extensions.models.factories import ModelFactory
 from openapi_core.schema.schemas.enums import SchemaFormat, SchemaType
@@ -44,10 +45,12 @@ class Schema(object):
 
     STRING_FORMAT_CALLABLE_GETTER = {
         SchemaFormat.NONE: Format(text_type, TypeValidator(text_type)),
-        SchemaFormat.DATE: Format(format_date, TypeValidator(date, exclude=datetime)),
+        SchemaFormat.DATE: Format(
+            format_date, TypeValidator(date, exclude=datetime)),
         SchemaFormat.DATETIME: Format(format_datetime, TypeValidator(datetime)),
         SchemaFormat.BINARY: Format(binary_type, TypeValidator(binary_type)),
         SchemaFormat.UUID: Format(UUID, TypeValidator(UUID)),
+        SchemaFormat.BYTE: Format(b64decode, TypeValidator(binary_type)),
     }
 
     TYPE_VALIDATOR_CALLABLE_GETTER = {
diff --git a/tests/integration/data/v3.0/petstore.yaml b/tests/integration/data/v3.0/petstore.yaml
index 733c587..3f132c3 100644
--- a/tests/integration/data/v3.0/petstore.yaml
+++ b/tests/integration/data/v3.0/petstore.yaml
@@ -78,8 +78,8 @@ paths:
         - name: api_key
           in: header
           schema:
-            type: integer
-            format: int32
+            type: string
+            format: byte
           required: true
         - name: user
           in: cookie
diff --git a/tests/integration/test_petstore.py b/tests/integration/test_petstore.py
index f1068c1..e1a3c8e 100644
--- a/tests/integration/test_petstore.py
+++ b/tests/integration/test_petstore.py
@@ -1,5 +1,6 @@
 import json
 import pytest
+from base64 import b64encode
 from uuid import UUID
 from six import iteritems
 
@@ -30,6 +31,12 @@ from openapi_core.wrappers.mock import MockRequest, MockResponse
 
 class TestPetstore(object):
 
+    api_key = b'12345'
+
+    @property
+    def api_key_encoded(self):
+        return b64encode(self.api_key)
+
     @pytest.fixture
     def spec_dict(self, factory):
         return factory.spec_from_file("data/v3.0/petstore.yaml")
@@ -424,7 +431,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -440,7 +447,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -484,7 +491,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -500,7 +507,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -544,7 +551,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -560,7 +567,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -592,7 +599,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -608,7 +615,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -631,7 +638,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -647,7 +654,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -672,7 +679,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -688,7 +695,7 @@ class TestPetstore(object):
 
         assert parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -711,7 +718,7 @@ class TestPetstore(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
 
         request = MockRequest(
diff --git a/tests/integration/test_validators.py b/tests/integration/test_validators.py
index 55a1199..bfdd4f9 100644
--- a/tests/integration/test_validators.py
+++ b/tests/integration/test_validators.py
@@ -1,3 +1,4 @@
+from base64 import b64encode
 import json
 import pytest
 
@@ -22,6 +23,12 @@ class TestRequestValidator(object):
 
     host_url = 'http://petstore.swagger.io'
 
+    api_key = b'12345'
+
+    @property
+    def api_key_encoded(self):
+        return b64encode(self.api_key)
+
     @pytest.fixture
     def spec_dict(self, factory):
         return factory.spec_from_file("data/v3.0/petstore.yaml")
@@ -88,7 +95,7 @@ class TestRequestValidator(object):
 
     def test_missing_body(self, validator):
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -106,7 +113,7 @@ class TestRequestValidator(object):
         assert result.body is None
         assert result.parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -115,7 +122,7 @@ class TestRequestValidator(object):
 
     def test_invalid_content_type(self, validator):
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -133,7 +140,7 @@ class TestRequestValidator(object):
         assert result.body is None
         assert result.parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
@@ -159,7 +166,7 @@ class TestRequestValidator(object):
         }
         data = json.dumps(data_json)
         headers = {
-            'api_key': '12345',
+            'api_key': self.api_key_encoded,
         }
         cookies = {
             'user': '123',
@@ -175,7 +182,7 @@ class TestRequestValidator(object):
         assert result.errors == []
         assert result.parameters == {
             'header': {
-                'api_key': 12345,
+                'api_key': self.api_key,
             },
             'cookie': {
                 'user': 123,
diff --git a/tests/unit/schema/test_schemas.py b/tests/unit/schema/test_schemas.py
index 47f4011..302719f 100644
--- a/tests/unit/schema/test_schemas.py
+++ b/tests/unit/schema/test_schemas.py
@@ -478,6 +478,25 @@ class TestSchemaValidate(object):
 
         assert result == value
 
+    @pytest.mark.parametrize('value', [
+        u('tsssst'), u('dGVzdA=='),
+    ])
+    def test_string_format_byte_invalid(self, value):
+        schema = Schema('string', schema_format='byte')
+
+        with pytest.raises(OpenAPISchemaError):
+            schema.validate(value)
+
+    @pytest.mark.parametrize('value', [
+        b('tsssst'), b('dGVzdA=='),
+    ])
+    def test_string_format_byte(self, value):
+        schema = Schema('string', schema_format='byte')
+
+        result = schema.validate(value)
+
+        assert result == value
+
     @pytest.mark.parametrize('value', [
         u('test'), b('stream'), datetime.date(1989, 1, 2),
         datetime.datetime(1989, 1, 2, 0, 0, 0),