diff --git a/packages/type-extrinsics/src/utils/createUnchecked.ts b/packages/type-extrinsics/src/utils/createUnchecked.ts
index 8166523c18..4521ba4e2a 100644
--- a/packages/type-extrinsics/src/utils/createUnchecked.ts
+++ b/packages/type-extrinsics/src/utils/createUnchecked.ts
@@ -22,11 +22,7 @@ export default function createDescriptor (
   const callIndex = new Uint8Array([index, meta.id.toNumber()]);
   let extrinsicFn: any;
 
-  // If the extrinsic function has an argument of type `Origin`, we ignore it
-  // FIXME should be `arg.type !== Origin`, but doesn't work...
-  const expectedArgs = meta.arguments.filter((arg) =>
-    arg.type.toString() !== 'Origin'
-  );
+  const expectedArgs = Method.filterOrigin(meta);
 
   extrinsicFn = (...args: any[]): Extrinsic => {
     if (expectedArgs.length.valueOf() !== args.length) {
diff --git a/packages/types/src/Extrinsic.spec.js b/packages/types/src/Extrinsic.spec.js
new file mode 100644
index 0000000000..4ee44310db
--- /dev/null
+++ b/packages/types/src/Extrinsic.spec.js
@@ -0,0 +1,15 @@
+// Copyright 2017-2018 @polkadot/types authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import Extrinsic from './Extrinsic';
+
+describe('Extrinsic', () => {
+  it('decodes a non-signed properly via fromJSON', () => {
+    const extrinsic = new Extrinsic().fromJSON('0x010200ea51b75b00000000');
+
+    expect(extrinsic.isSigned).toEqual(false);
+    expect(extrinsic.callIndex).toEqual(new Uint8Array([2, 0]));
+    expect(extrinsic.data).toEqual(new Uint8Array([234, 81, 183, 91, 0, 0, 0, 0]));
+  });
+});
diff --git a/packages/types/src/Extrinsic.ts b/packages/types/src/Extrinsic.ts
index 3984bae1f1..e669eec077 100644
--- a/packages/types/src/Extrinsic.ts
+++ b/packages/types/src/Extrinsic.ts
@@ -6,6 +6,7 @@ import { KeyringPair } from '@polkadot/util-keyring/types';
 import { AnyNumber, AnyU8a } from './types';
 
 import blake2Asu8a from '@polkadot/util-crypto/blake2/asU8a';
+import hexToU8a from '@polkadot/util/hex/toU8a';
 import u8aConcat from '@polkadot/util/u8a/concat';
 import u8aToHex from '@polkadot/util/u8a/toHex';
 
@@ -42,8 +43,13 @@ export default class Extrinsic extends Struct {
     }, value);
   }
 
-  get method (): Method {
-    return this.raw.method as Method;
+  // the actual [sectionIndex, methodIndex] as used
+  get callIndex (): Uint8Array {
+    return this.method.callIndex;
+  }
+
+  get data (): Uint8Array {
+    return this.method.data;
   }
 
   // convernience, encodes the extrinsic and returns the actual hash
@@ -53,6 +59,10 @@ export default class Extrinsic extends Struct {
     );
   }
 
+  get isSigned (): boolean {
+    return this.signature.isSigned;
+  }
+
   get length (): number {
     return this.toU8a(true).length;
   }
@@ -61,9 +71,8 @@ export default class Extrinsic extends Struct {
     return this.method.meta;
   }
 
-  // the actual [sectionIndex, methodIndex] as used
-  get callIndex (): Uint8Array {
-    return this.method.callIndex;
+  get method (): Method {
+    return this.raw.method as Method;
   }
 
   get signature (): ExtrinsicSignature {
@@ -76,6 +85,12 @@ export default class Extrinsic extends Struct {
     return length + Compact.encode(length).length;
   }
 
+  fromJSON (input: any): Extrinsic {
+    super.fromU8a(hexToU8a(input));
+
+    return this;
+  }
+
   fromU8a (input: Uint8Array): Extrinsic {
     const [offset, length] = Compact.decode(input);
 
@@ -102,7 +117,7 @@ export default class Extrinsic extends Struct {
   }
 
   toHex (): string {
-    return u8aToHex(this.toU8a());
+    return u8aToHex(this.toU8a(true));
   }
 
   toJSON (): any {
diff --git a/packages/types/src/ExtrinsicSignature.ts b/packages/types/src/ExtrinsicSignature.ts
index 1673404d26..0b8b859b8d 100644
--- a/packages/types/src/ExtrinsicSignature.ts
+++ b/packages/types/src/ExtrinsicSignature.ts
@@ -43,6 +43,15 @@ export default class ExtrinsicSignature extends Struct {
     }, value);
   }
 
+  byteLength (): number {
+    // version has 1 byte, signature takes the rest
+    return 1 + (
+      this.isSigned
+        ? super.byteLength()
+        : 0
+    );
+  }
+
   get isSigned (): boolean {
     return this.signature.length !== 0;
   }
diff --git a/packages/types/src/Method.ts b/packages/types/src/Method.ts
index cd84cc1cd5..2084c117bb 100644
--- a/packages/types/src/Method.ts
+++ b/packages/types/src/Method.ts
@@ -9,7 +9,7 @@ import u8aConcat from '@polkadot/util/u8a/concat';
 import createType from './codec/createType';
 import Base from './codec/Base';
 import MethodIndex from './MethodIndex';
-import { FunctionMetadata } from './Metadata';
+import { FunctionMetadata, FunctionArgumentMetadata } from './Metadata';
 
 /**
  * Extrinsic function descriptor, as defined in
@@ -17,6 +17,7 @@ import { FunctionMetadata } from './Metadata';
  */
 export default class Method extends MethodIndex {
   protected _args: Array<Base>;
+  protected _data: Uint8Array;
   protected _meta: FunctionMetadata;
 
   constructor (index: Method | AnyU8a, meta: FunctionMetadata, args: Array<any>) {
@@ -29,35 +30,72 @@ export default class Method extends MethodIndex {
       this._args = args;
       this._meta = meta;
     }
+
+    this._data = Method.encode(this._meta, this._args);
   }
 
-  get args () {
+  static decode (meta: FunctionMetadata, data: Uint8Array): Array<Base> {
+    let offset = 0;
+
+    return Method.filterOrigin(meta).map(({ type }) => {
+      const base = createType(type).fromU8a(data.subarray(offset));
+
+      offset += base.byteLength();
+
+      return base;
+    });
+  }
+
+  static encode (meta: FunctionMetadata, args: Array<any>): Uint8Array {
+    const encoded = Method.filterOrigin(meta).map(({ type }, index) =>
+      createType(type, args[index]).toU8a()
+    );
+
+    return u8aConcat(...encoded);
+  }
+
+  // If the extrinsic function has an argument of type `Origin`, we ignore it
+  static filterOrigin (meta?: FunctionMetadata): Array<FunctionArgumentMetadata> {
+    // FIXME should be `arg.type !== Origin`, but doesn't work...
+    return meta
+      ? meta.arguments.filter(({ type }) =>
+        type.toString() !== 'Origin'
+      )
+      : [];
+  }
+
+  byteLength (): number {
+    return super.byteLength() + this.data.length;
+  }
+
+  get args (): Array<any> {
     return this._args;
   }
 
-  get index () {
+  get data (): Uint8Array {
+    return this._data;
+  }
+
+  get index (): Uint8Array {
     return this.raw;
   }
 
-  get meta () {
+  get meta (): FunctionMetadata {
     return this._meta;
   }
 
-  toU8a (isBare?: boolean): Uint8Array {
-    // FIXME Even when decoded, we will need access to the meta
-    const args = this.meta
-      ? this.meta.arguments
-        .filter((arg) =>
-          arg.type.toString() !== 'Origin'
-        )
-        .map((argument, index) =>
-          createType(argument.type, this.args[index]).toU8a(isBare)
-        )
-      : [];
+  fromU8a (input: Uint8Array): Method {
+    super.fromU8a(input);
 
+    this._data = input.subarray(super.byteLength());
+
+    return this;
+  }
+
+  toU8a (isBare?: boolean): Uint8Array {
     return u8aConcat(
       super.toU8a(isBare),
-      ...args
+      this.data
     );
   }
 }
diff --git a/packages/types/src/codec/U8aFixed.ts b/packages/types/src/codec/U8aFixed.ts
index 4598cb112d..9a79b2c044 100644
--- a/packages/types/src/codec/U8aFixed.ts
+++ b/packages/types/src/codec/U8aFixed.ts
@@ -18,27 +18,31 @@ export default class U8aFixed extends U8a {
 
     this._bitLength = bitLength;
 
-    this._trimLength();
+    this._trim();
   }
 
-  private _trimLength (): void {
-    this.raw = this.raw.subarray(0, this.byteLength());
+  private _trimLength (): number {
+    return this._bitLength / 8;
+  }
+
+  private _trim (): void {
+    this.raw = this.raw.subarray(0, this._trimLength());
   }
 
   byteLength (): number {
-    return this._bitLength / 8;
+    return this._trimLength();
   }
 
   fromJSON (input: any): U8aFixed {
     super.fromJSON(input);
 
-    this._trimLength();
+    this._trim();
 
     return this;
   }
 
   fromU8a (input: Uint8Array): U8aFixed {
-    super.fromU8a(input.subarray(0, this.byteLength()));
+    super.fromU8a(input.subarray(0, this._trimLength()));
 
     return this;
   }