diff --git a/doc/README.md b/doc/README.md
index 06fda515..c4b38c3e 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -1894,6 +1894,28 @@ steem.broadcast.feedPublish(wif, publisher, exchangeRate, function(err, result)
 });
 ```
 - - - - - - - - - - - - - - - - - -
+### Build Witness Update Properties
+```
+const owner = 'starlord28'
+const props = {
+  "key": "Public Signing Key", // MANDATORY
+  "new_signing_key": "Public Signing Key", // optional
+  "account_creation_fee": "3.000 STEEM", // optional
+  "account_subsidy_budget": 0, // optional
+  "account_subsidy_decay": 0, // optional
+  "maximum_block_size": 65536, // optional
+  "sbd_interest_rate": "0.000 STEEM", // optional
+  "sbd_exchange_rate": {"base": "0.237 SBD", "quote": "1.000 STEEM"}, // optional
+  "url": "https://steemcryptic.me", // optional
+}
+
+const witnessOps = steem.utils.buildWitnessSetProperties(props);
+
+steem.broadcast.witnessSetProperties('Private Signing Key', owner, witnessOps, [], function(err, result) {
+  console.log(err, result);
+});
+```
+- - - - - - - - - - - - - - - - - -
 ### Fill Convert Request
 ```js
 steem.broadcast.fillConvertRequest(wif, owner, requestid, amountIn, amountOut, function(err, result) {
diff --git a/package.json b/package.json
index bd194091..64e582c4 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@steemit/steem-js",
-  "version": "0.7.11",
+  "version": "0.7.12",
   "description": "Steem.js the JavaScript API for Steem blockchain",
   "main": "lib/index.js",
   "scripts": {
diff --git a/src/auth/serializer/src/operations.js b/src/auth/serializer/src/operations.js
index b6573e06..a76299d9 100644
--- a/src/auth/serializer/src/operations.js
+++ b/src/auth/serializer/src/operations.js
@@ -661,7 +661,7 @@ let account_create_with_delegation = new Serializer(
 let witness_set_properties = new Serializer(
     "witness_set_properties", {
     owner: string,
-    props: string,
+    props: map(string, bytes()),
     extensions: set(future_extensions)
 }
 );
diff --git a/src/utils.js b/src/utils.js
index 253541ff..be45aaf6 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -1,3 +1,25 @@
+
+import types from "./auth/serializer/src/types"
+import Serializer from "./auth/serializer/src/serializer"
+import ByteBuffer from '@exodus/bytebuffer'
+
+let price = new Serializer(
+  "price", {
+  base: types.asset,
+  quote: types.asset
+}
+);
+const propTypes = {
+  key: types.public_key,
+  new_signing_key: types.public_key,
+  account_creation_fee: types.asset,
+  account_subsidy_budget: types.uint32,
+  account_subsidy_decay: types.uint32,
+  maximum_block_size: types.uint32,
+  sbd_interest_rate: types.uint16,
+  sbd_exchange_rate: price,
+  url: types.string
+};
 const snakeCaseRe = /_([a-z])/g;
 export function camelCase(str) {
   return str.replace(snakeCaseRe, function(_m, l) {
@@ -43,3 +65,31 @@ export function validateAccountName(value) {
   }
   return null;
 }
+
+function serialize(serializer, data) {
+  const buffer = new ByteBuffer(
+    ByteBuffer.DEFAULT_CAPACITY,
+    ByteBuffer.LITTLE_ENDIAN
+  );
+  serializer.appendByteBuffer(buffer, data);
+  buffer.flip();
+  return buffer.toString('hex');
+}
+
+export function buildWitnessSetProperties(props) {
+  const data = [];
+
+  for (const [key, value] of Object.entries(props)) {
+    const type = propTypes[key];
+
+    if (!type) {
+      throw new Error(`Unknown witness property: ${key}`);
+    }
+
+    data.push([key, serialize(type, value)]);
+  }
+
+  data.sort((a, b) => a[0].localeCompare(b[0]));
+
+  return data;
+}