diff --git a/Substrate.NetApi.Test/Extrinsic/InstanceTest.cs b/Substrate.NetApi.Test/Extrinsic/InstanceTest.cs
index 6b206f9..8294fcf 100644
--- a/Substrate.NetApi.Test/Extrinsic/InstanceTest.cs
+++ b/Substrate.NetApi.Test/Extrinsic/InstanceTest.cs
@@ -11,14 +11,15 @@ namespace Substrate.NetApi.Test.Extrinsic
     public class InstanceTest
     {
 
+        // Extrinsics created and signed with polkadot-js/apps.
         public static string[] Extrinsic = new string[]
         {
             // Timestamp set(now) with now = 1673908758014
-            "0x280403000bfea5bcbc8501",
+            "0xc50184001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c0188f4859d09355d8f964b8cbb8b84c5e0e2f86a423d30027d15764996dc198532044424e6cc2e281f4d23174b6bfb3d2af64917b7356e570f41a1e44bcaa47385650300000001000bfea5bcbc8501",
             // Staking bondExtra(maxAdditional) with maxAditional = 60000000000
-            "0xbd01840021e64ca11afde772615b240dd09ada3fc96e46619b77f9c0ce3dcebc67878939006ac2017f7951358d09ca1c6da63501b8d00dd72703e593b4a0ca924d59360d4968abaf6361999a21943618ce0850f8b5f8dd51c54c772ffccb35ff63208a1d0025012000070107005847f80d",
+            "0x710284001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c01d0e951a27297d1418d17fcbadfc19441d2d276f358965a94ff87f1b1db287c4cae203b65dab926627c80deae720bca1335d771389843b1bf69b9e85139922b819503000000070000001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c0a000000000000000000000000000000",
             // Balances transferKeepAlive(dest, value)
-            "0x45028400f371affe2fd3ebd6f0a607e983bc8f905cea0ca2668667a229e112b30c5f9bbd0096f3ac43319d2e980db0aaf2b7e5e985055ea87f7b2a91a2ee09a934aef55bad4ec0dfd93e7010bc5dbf290403051ec40d475534df90ce3e1dd8a5b1ab3f7a0e4502cd0e000503001c3ef60163945e2b4602f7c6b27fc1f8e79d7c3430e3518cf63dc8a6ee84e9740700325f9d08"
+            "0x4d0284001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c01e6da8673127ec665dbfb76322ffe12721caa9b747abc5b6ec8ab73ff34f07831ed9edc49d185483a0c538a120149b7b6367bcde7088873408cc49ec280976c8ba5000000000403001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c0f0080c6a47e8d03"
         };
 
         [Test]
diff --git a/Substrate.NetApi.Test/Extrinsic/PayloadTest.cs b/Substrate.NetApi.Test/Extrinsic/PayloadTest.cs
index 7c86299..a3e375d 100644
--- a/Substrate.NetApi.Test/Extrinsic/PayloadTest.cs
+++ b/Substrate.NetApi.Test/Extrinsic/PayloadTest.cs
@@ -59,7 +59,7 @@ public void EncodeExtraTest()
             var payload = new Payload(method, signedExtensions);
 
             var payloadBytes = Utils.StringValueArrayBytesArray(
-                "6, 0, 255, 212, 53, 147, 199, 21, 253, 211, 28, 97, 20, 26, 189, 4, 169, 159, 214, 130, 44, 133, 88, 133, 76, 205, 227, 154, 86, 132, 231, 165, 109, 162, 125, 145, 1, 58, 6, 0, 0, 0, 3, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0");
+                "6, 0, 255, 212, 53, 147, 199, 21, 253, 211, 28, 97, 20, 26, 189, 4, 169, 159, 214, 130, 44, 133, 88, 133, 76, 205, 227, 154, 86, 132, 231, 165, 109, 162, 125, 145, 1, 58, 6, 0, 0, 0, 0, 3, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0");
 
             Assert.AreEqual(payloadBytes, payload.Encode());
         }
diff --git a/Substrate.NetApi.Test/Extrinsic/SignedExtensionsTest.cs b/Substrate.NetApi.Test/Extrinsic/SignedExtensionsTest.cs
index 0ddf35c..c3aa7db 100644
--- a/Substrate.NetApi.Test/Extrinsic/SignedExtensionsTest.cs
+++ b/Substrate.NetApi.Test/Extrinsic/SignedExtensionsTest.cs
@@ -41,10 +41,10 @@ public void EncodeExtraTest()
             var signedExtensions = new SignedExtensions(259, 1, genesis, startEra, era, 0, assetTxPayment);
 
             var bytes = Utils.StringValueArrayBytesArray(
-                "58, 6, 0, 0, 0, 3, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0");
+                "58, 6, 0, 0, 0, 0, 3, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0");
 
-            Assert.AreEqual(bytes.AsMemory().Slice(0, 5).ToArray(), signedExtensions.GetExtra());
-            Assert.AreEqual(bytes.AsMemory().Slice(5, 72).ToArray(), signedExtensions.GetAdditionalSigned());
+            Assert.AreEqual(bytes.AsMemory().Slice(0, 6).ToArray(), signedExtensions.GetExtra());
+            Assert.AreEqual(bytes.AsMemory().Slice(6, 73).ToArray(), signedExtensions.GetAdditionalSigned());
             Assert.AreEqual(bytes, signedExtensions.Encode());
         }
     }
diff --git a/Substrate.NetApi/Model/Extrinsics/CheckMetadataHash.cs b/Substrate.NetApi/Model/Extrinsics/CheckMetadataHash.cs
new file mode 100644
index 0000000..d7085af
--- /dev/null
+++ b/Substrate.NetApi/Model/Extrinsics/CheckMetadataHash.cs
@@ -0,0 +1,76 @@
+using Substrate.NetApi.Model.Types.Base;
+using System;
+
+namespace Substrate.NetApi.Model.Extrinsics
+{
+
+    /// <summary>
+    ///  If the runtime should expect a metadata hash that has been signed in the additional signed.
+    /// </summary>  
+    public enum Mode
+    {
+        /// <summary>
+        ///  `None` has been signed in the CheckMetadataHash additional signed.
+        /// </summary>  
+        Disabled,
+        /// <summary>
+        ///  `Some(MetadataHash)` has been signed in the CheckMetadataHash additional signed.
+        /// </summary>  
+        Enabled
+    }
+    /// <summary>
+    /// CheckMetadataHash signed extension.
+    /// </summary>
+    public class CheckMetadataHash: BaseType
+    {
+        private Mode _mode;
+
+        /// <summary>
+        /// Initialize with `Mode.Disabled`.
+        /// </summary>
+        public CheckMetadataHash() { 
+            // Don't allow enabling the mode, as we don't support it.
+            _mode = Mode.Disabled;
+        }
+
+        /// <summary>
+        /// Corresponds to the `Extra` that is sent with the extrinsic.
+        /// </summary>
+        /// <returns></returns>
+        public override byte[] Encode()
+        {
+            return EncodeExtra();
+        }
+
+        /// <summary>
+        /// Corresponds to the extra that _is_ sent with the extrinsic.
+        /// </summary>
+        /// <returns></returns>
+        public byte[] EncodeExtra()
+        {
+            return new BaseEnum<Mode>(_mode).Encode();
+        }
+
+        /// <summary>
+        /// Corresponds to the `Additional` that is signed, but _not_ sent with the extrinsic.
+        /// </summary>
+        /// <returns></returns>
+        public byte[] EncodeAdditional()
+        {
+            // We provide no metadata hash in the signer payload to align with the above.
+            return new byte[1];
+        }
+
+        /// <inheritdoc />
+        public override void Decode(byte[] byteArray, ref int p)
+        {
+            uint modeByte = byteArray[p++];
+
+            if (modeByte > 1) {
+                throw new ArgumentException($"{modeByte} is not a valid representation of CheckMetadata Mode.");
+            }
+
+            _mode = modeByte == 0 ? Mode.Disabled : Mode.Enabled;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Substrate.NetApi/Model/Extrinsics/Extrinsic.cs b/Substrate.NetApi/Model/Extrinsics/Extrinsic.cs
index fd9d3cc..e689ad4 100644
--- a/Substrate.NetApi/Model/Extrinsics/Extrinsic.cs
+++ b/Substrate.NetApi/Model/Extrinsics/Extrinsic.cs
@@ -44,6 +44,11 @@ public class Extrinsic
         /// Method
         /// </summary>
         public Method Method { get; set; }
+        
+        /// <summary>
+        /// CheckMetadataHash
+        /// </summary>
+        public CheckMetadataHash CheckMetadataHash { get; set; }
 
         /// <summary>
         /// Signature
@@ -124,6 +129,9 @@ internal Extrinsic(Memory<byte> memory, ChargeType chargeType)
                 // charge type
                 Charge = chargeType;
                 Charge.Decode(memory.ToArray(), ref p);
+
+                CheckMetadataHash = new CheckMetadataHash();
+                CheckMetadataHash.Decode(memory.ToArray(), ref p);
             }
 
             // method
@@ -154,6 +162,7 @@ public Extrinsic(bool signed, Account account, CompactInteger nonce, Method meth
             Era = era;
             Nonce = nonce;
             Charge = charge;
+            CheckMetadataHash = new CheckMetadataHash();
             Method = method;
         }
 
@@ -176,6 +185,7 @@ public byte[] Encode()
                 result.AddRange(Era.Encode());
                 result.AddRange(Nonce.Encode());
                 result.AddRange(Charge.Encode());
+                result.AddRange(CheckMetadataHash.EncodeExtra());
             }
 
             result.AddRange(Method.Encode());
diff --git a/Substrate.NetApi/Model/Extrinsics/SignedExtensions.cs b/Substrate.NetApi/Model/Extrinsics/SignedExtensions.cs
index bc6bc5c..3e59f29 100644
--- a/Substrate.NetApi/Model/Extrinsics/SignedExtensions.cs
+++ b/Substrate.NetApi/Model/Extrinsics/SignedExtensions.cs
@@ -42,6 +42,11 @@ public class SignedExtensions
         /// Charge
         /// </summary>
         public ChargeType Charge { get; }
+        
+        /// <summary>
+        /// CheckMetadataHash; only disabled supported for now.
+        /// </summary>
+        public CheckMetadataHash MetadataHashSignedExt { get; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="SignedExtensions"/> class.
@@ -62,6 +67,7 @@ public SignedExtensions(uint specVersion, uint txVersion, Hash genesis, Hash sta
             Mortality = mortality;
             Nonce = nonce;
             Charge = charge;
+            MetadataHashSignedExt = new CheckMetadataHash();
         }
 
         /// <summary>
@@ -80,6 +86,9 @@ public byte[] GetExtra()
 
             // ChargeType
             bytes.AddRange(Charge.Encode());
+            
+            // CheckMetadataHash
+            bytes.AddRange(MetadataHashSignedExt.EncodeExtra());
 
             return bytes.ToArray();
         }
@@ -103,6 +112,9 @@ public byte[] GetAdditionalSigned()
 
             // CheckMortality, Additional Blockhash check. Immortal = genesis_hash, Mortal = logic
             bytes.AddRange(StartEra.Bytes);
+            
+            // CheckMetadataHash
+            bytes.AddRange(MetadataHashSignedExt.EncodeAdditional());
 
             return bytes.ToArray();
         }
diff --git a/Substrate.NetApi/Model/Extrinsics/UnCheckedExtrinsic.cs b/Substrate.NetApi/Model/Extrinsics/UnCheckedExtrinsic.cs
index 2175740..ab8d809 100644
--- a/Substrate.NetApi/Model/Extrinsics/UnCheckedExtrinsic.cs
+++ b/Substrate.NetApi/Model/Extrinsics/UnCheckedExtrinsic.cs
@@ -93,8 +93,10 @@ public void AddPayloadSignature(byte[] signature)
 
             list.AddRange(Charge.Encode());
 
+            list.AddRange(CheckMetadataHash.EncodeExtra());
+            
             list.AddRange(Method.Encode());
-
+            
             return Utils.SizePrefixedByteArray(list);
         }
     }