diff --git a/Octokit.Tests.Integration/Clients/CommitCommentReactionsClientTests.cs b/Octokit.Tests.Integration/Clients/CommitCommentReactionsClientTests.cs
index 14e749b6..679070a6 100644
--- a/Octokit.Tests.Integration/Clients/CommitCommentReactionsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/CommitCommentReactionsClientTests.cs
@@ -56,14 +56,16 @@ public class CommitCommentReactionsClientTests
 
             Assert.NotNull(result);
 
-            var newReaction = new NewReaction(ReactionType.Confused);
-            var reaction = await _github.Reaction.CommitComment.Create(_context.RepositoryOwner, _context.RepositoryName, result.Id, newReaction);
+            foreach (ReactionType reactionType in Enum.GetValues(typeof(ReactionType)))
+            {
+                var newReaction = new NewReaction(reactionType);
 
-            Assert.IsType<Reaction>(reaction);
+                var reaction = await _github.Reaction.CommitComment.Create(_context.RepositoryOwner, _context.RepositoryName, result.Id, newReaction);
 
-            Assert.Equal(ReactionType.Confused, reaction.Content);
-
-            Assert.Equal(result.User.Id, reaction.User.Id);
+                Assert.IsType<Reaction>(reaction);
+                Assert.Equal(reactionType, reaction.Content);
+                Assert.Equal(result.User.Id, reaction.User.Id);
+            }
         }
 
         public void Dispose()
diff --git a/Octokit.Tests.Integration/Clients/IssueCommentReactionsClientTests.cs b/Octokit.Tests.Integration/Clients/IssueCommentReactionsClientTests.cs
index 210a551e..6502e867 100644
--- a/Octokit.Tests.Integration/Clients/IssueCommentReactionsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/IssueCommentReactionsClientTests.cs
@@ -33,15 +33,16 @@ public class IssueCommentReactionsClientTests
 
             Assert.NotNull(issueComment);
 
-            var issueCommentReaction = await _github.Reaction.IssueComment.Create(_context.RepositoryOwner, _context.RepositoryName, issueComment.Id, new NewReaction(ReactionType.Heart));
+            foreach (ReactionType reactionType in Enum.GetValues(typeof(ReactionType)))
+            {
+                var newReaction = new NewReaction(reactionType);
 
-            Assert.NotNull(issueCommentReaction);
+                var reaction = await _github.Reaction.CommitComment.Create(_context.RepositoryOwner, _context.RepositoryName, issueComment.Id, newReaction);
 
-            Assert.IsType<Reaction>(issueCommentReaction);
-
-            Assert.Equal(ReactionType.Heart, issueCommentReaction.Content);
-
-            Assert.Equal(issueComment.User.Id, issueCommentReaction.User.Id);
+                Assert.IsType<Reaction>(reaction);
+                Assert.Equal(reactionType, reaction.Content);
+                Assert.Equal(issueComment.User.Id, reaction.User.Id);
+            }
         }
 
         public void Dispose()
diff --git a/Octokit.Tests.Integration/Clients/IssueReactionsClientTests.cs b/Octokit.Tests.Integration/Clients/IssueReactionsClientTests.cs
index 32f263fa..e6b9b806 100644
--- a/Octokit.Tests.Integration/Clients/IssueReactionsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/IssueReactionsClientTests.cs
@@ -29,15 +29,16 @@ public class IssueReactionsClientTests
 
             Assert.NotNull(issue);
 
-            var issueReaction = await _github.Reaction.Issue.Create(_context.RepositoryOwner, _context.RepositoryName, issue.Number, new NewReaction(ReactionType.Heart));
+            foreach (ReactionType reactionType in Enum.GetValues(typeof(ReactionType)))
+            {
+                var newReaction = new NewReaction(reactionType);
 
-            Assert.NotNull(issueReaction);
+                var reaction = await _github.Reaction.CommitComment.Create(_context.RepositoryOwner, _context.RepositoryName, issue.Id, newReaction);
 
-            Assert.IsType<Reaction>(issueReaction);
-
-            Assert.Equal(ReactionType.Heart, issueReaction.Content);
-
-            Assert.Equal(issue.User.Id, issueReaction.User.Id);
+                Assert.IsType<Reaction>(reaction);
+                Assert.Equal(reactionType, reaction.Content);
+                Assert.Equal(issue.User.Id, reaction.User.Id);
+            }
         }
 
         public void Dispose()
diff --git a/Octokit.Tests.Integration/Clients/PullRequestReviewCommentReactionsClientTests.cs b/Octokit.Tests.Integration/Clients/PullRequestReviewCommentReactionsClientTests.cs
index b705bfa8..84afbcda 100644
--- a/Octokit.Tests.Integration/Clients/PullRequestReviewCommentReactionsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/PullRequestReviewCommentReactionsClientTests.cs
@@ -40,15 +40,16 @@ public class PullRequestReviewCommentReactionsClientTests : IDisposable
 
         AssertComment(commentFromGitHub, body, position);
 
-        var pullRequestReviewCommentReaction = await _github.Reaction.PullRequestReviewComment.Create(_context.RepositoryOwner, _context.RepositoryName, commentFromGitHub.Id, new NewReaction(ReactionType.Heart));
+        foreach (ReactionType reactionType in Enum.GetValues(typeof(ReactionType)))
+        {
+            var newReaction = new NewReaction(reactionType);
 
-        Assert.NotNull(pullRequestReviewCommentReaction);
+            var reaction = await _github.Reaction.CommitComment.Create(_context.RepositoryOwner, _context.RepositoryName, commentFromGitHub.Id, newReaction);
 
-        Assert.IsType<Reaction>(pullRequestReviewCommentReaction);
-
-        Assert.Equal(ReactionType.Heart, pullRequestReviewCommentReaction.Content);
-
-        Assert.Equal(commentFromGitHub.User.Id, pullRequestReviewCommentReaction.User.Id);
+            Assert.IsType<Reaction>(reaction);
+            Assert.Equal(reactionType, reaction.Content);
+            Assert.Equal(commentFromGitHub.User.Id, reaction.User.Id);
+        }
     }
 
     /// <summary>
diff --git a/Octokit/Http/SimpleJsonSerializer.cs b/Octokit/Http/SimpleJsonSerializer.cs
index 5835bcac..8253bdad 100644
--- a/Octokit/Http/SimpleJsonSerializer.cs
+++ b/Octokit/Http/SimpleJsonSerializer.cs
@@ -24,6 +24,7 @@ namespace Octokit.Internal
         class GitHubSerializerStrategy : PocoJsonSerializerStrategy
         {
             readonly List<string> _membersWhichShouldPublishNull = new List<string>();
+            Dictionary<Type, Dictionary<object, object>> _cachedEnums = new Dictionary<Type, Dictionary<object, object>>();
 
             protected override string MapClrMemberToJsonFieldName(MemberInfo member)
             {
@@ -78,7 +79,7 @@ namespace Octokit.Internal
                 Justification = "The API expects lowercase values")]
             protected override object SerializeEnum(Enum p)
             {
-                return p.ToString().ToLowerInvariant();
+                return p.ToParameter();
             }
 
             private string _type;
@@ -88,13 +89,43 @@ namespace Octokit.Internal
             {
                 var stringValue = value as string;
                 var jsonValue = value as JsonObject;
+
                 if (stringValue != null)
                 {
                     if (ReflectionUtils.GetTypeInfo(type).IsEnum)
                     {
-                        // remove '-' from values coming in to be able to enum utf-8
-                        stringValue = RemoveHyphenAndUnderscore(stringValue);
-                        return Enum.Parse(type, stringValue, ignoreCase: true);
+                        if (!_cachedEnums.ContainsKey(type))
+                        {
+                            //First add type to Dictionary
+                            _cachedEnums.Add(type, new Dictionary<object, object>());
+                            //then try to get all custom attributes, this happens only once per type
+                            var fields = type.GetRuntimeFields();
+                            foreach (var field in fields)
+                            {
+                                if (field.Name == "value__")
+                                    continue;
+                                var attribute = (ParameterAttribute)field.GetCustomAttribute(typeof(ParameterAttribute));
+                                if (attribute != null)
+                                {
+                                    if (attribute.Value.Equals(value))
+                                        _cachedEnums[type].Add(attribute.Value, field.GetValue(null));
+
+                                }
+                            }
+                        }
+                        if (_cachedEnums[type].ContainsKey(value))
+                        {
+                            return _cachedEnums[type][value];
+                        }
+                        else
+                        {
+                            //dictionary does not contain enum value and has no custom attribute. So add it for future loops and return value
+                            // remove '-' from values coming in to be able to enum utf-8
+                            stringValue = RemoveHyphenAndUnderscore(stringValue);
+                            var parsed = Enum.Parse(type, stringValue, ignoreCase: true);
+                            _cachedEnums[type].Add(value, parsed);
+                            return parsed;
+                        }
                     }
 
                     if (ReflectionUtils.IsNullableType(type))
diff --git a/Octokit/Models/Request/NewReaction.cs b/Octokit/Models/Request/NewReaction.cs
index 45607c14..7434da0c 100644
--- a/Octokit/Models/Request/NewReaction.cs
+++ b/Octokit/Models/Request/NewReaction.cs
@@ -18,7 +18,7 @@ namespace Octokit
         /// <summary>
         /// The reaction type (required)
         /// </summary>
-        public ReactionType Content { get; private set; }        
+        public ReactionType Content { get; private set; }
 
         internal string DebuggerDisplay
         {