diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index dba98719..0d892037 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2021-10-31 21:29:49 UTC using RuboCop version 1.22.3.
+# on 2021-11-01 06:50:04 UTC using RuboCop version 1.22.3.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -266,7 +266,7 @@ Layout/InitialIndentation:
   Exclude:
     - 'lib/oauth/request_proxy/curb_request.rb'
 
-# Offense count: 11
+# Offense count: 10
 # Cop supports --auto-correct.
 # Configuration parameters: AllowDoxygenCommentStyle, AllowGemfileRubyComment.
 Layout/LeadingCommentSpace:
@@ -275,7 +275,6 @@ Layout/LeadingCommentSpace:
     - '**/*.markdown'
     - 'lib/oauth/helper.rb'
     - 'lib/oauth/request_proxy.rb'
-    - 'oauth.gemspec'
     - 'test/cases/spec/1_0-final/test_construct_request_url.rb'
     - 'test/units/test_request_token.rb'
 
@@ -559,12 +558,12 @@ Lint/UselessMethodDefinition:
 # Offense count: 50
 # Configuration parameters: IgnoredMethods, CountRepeatedAttributes.
 Metrics/AbcSize:
-  Max: 59
+  Max: 63
 
 # Offense count: 9
 # Configuration parameters: CountComments, CountAsOne.
 Metrics/ClassLength:
-  Max: 282
+  Max: 284
 
 # Offense count: 7
 # Configuration parameters: IgnoredMethods.
@@ -584,7 +583,7 @@ Metrics/ParameterLists:
 # Offense count: 7
 # Configuration parameters: IgnoredMethods.
 Metrics/PerceivedComplexity:
-  Max: 18
+  Max: 20
 
 # Offense count: 16
 # Cop supports --auto-correct.
@@ -760,14 +759,13 @@ Style/AndOr:
     - 'lib/oauth/consumer.rb'
     - 'lib/oauth/request_proxy/rack_request.rb'
 
-# Offense count: 9
+# Offense count: 8
 # Cop supports --auto-correct.
 Style/ArrayJoin:
   Exclude:
     - 'lib/oauth/cli/base_command.rb'
     - 'lib/oauth/cli/sign_command.rb'
     - 'lib/oauth/client/net_http.rb'
-    - 'lib/oauth/errors/unauthorized.rb'
     - 'lib/oauth/helper.rb'
     - 'lib/oauth/request_proxy/base.rb'
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1b5e4bf3..b4c0b5c7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Setup Rubocop (#205, #208 by @pboling)
 * Added CODE_OF_CONDUCT.md (#217, #218 by @pboling)
 * Added FUNDING.yml (#217, #218 by @pboling)
+* Added Client Certificate Options: :ssl_client_cert and :ssl_client_key (#136, #220 by @pboling)
 
 ### Changed
 
diff --git a/lib/oauth/consumer.rb b/lib/oauth/consumer.rb
index 0e578a52..14eddea1 100644
--- a/lib/oauth/consumer.rb
+++ b/lib/oauth/consumer.rb
@@ -383,6 +383,8 @@ def create_http(_url = nil)
       http_object.read_timeout = http_object.open_timeout = @options[:timeout] || 60
       http_object.open_timeout = @options[:open_timeout] if @options[:open_timeout]
       http_object.ssl_version = @options[:ssl_version] if @options[:ssl_version]
+      http_object.cert = @options[:ssl_client_cert] if @options[:ssl_client_cert]
+      http_object.key  = @options[:ssl_client_key] if @options[:ssl_client_key]
       http_object.set_debug_output(debug_output) if debug_output
 
       http_object