diff --git a/README.md b/README.md
index 25e14b3..7b1cd01 100644
--- a/README.md
+++ b/README.md
@@ -77,9 +77,53 @@ shh.post({
 
 
 #### Polling for gas relayers
-TODO
+The first step is asking the relayers for their availability. The message payload needs to be the hex string representation of a JSON object with a specific structure:
 
+```
+const payload = web3.utils.toHex({
+        'contract': "0xContractToInvoke",
+        'address': web3.eth.defaultAccount,
+        'action': 'availability',
+        'token': "0xGasTokenAddress",
+        'gasPrice': 1234
+    });
+```
 
+- `contract` is the address of the contract that will perform the operation, in this case it can be an Identity, or the SNTController.
+- `address` The address that will sign the transactions. Normally it's `web3.eth.defaultAccount`
+- `gasToken`: token used for paying the gas cost
+- `gasPrice`: The gas price used for the transaction
+
+This is a example code of how to send an 'availability' message:
+
+```
+const whisperKeyPairID = await web3W.shh.newKeyPair();
+
+const msgObj = { 
+    symKeyId: "0xd0d905c1c62b810b787141430417caf2b3f54cffadb395b7bb39fdeb8f17266b", 
+    sig: whisperKeyPairID,
+    ttl: 1000, 
+    powTarget: 1, 
+    powTime: 20, 
+    topic: "0x4964656e", 
+    payload: web3.utils.toHex({
+        'contract': "0x692a70d2e424a56d2c6c27aa97d1a86395877b3a",
+        'address': web3.eth.defaultAccount
+        'action': 'availability',
+        'gasToken': "0x744d70fdbe2ba4cf95131626614a1763df805b9e",
+        'gasPrice': 40000000000 // 40 gwei equivalent in SNT
+    })
+};
+
+        
+web3.shh.post(msgObj)
+.then((err, result) => {
+    console.log(result);
+    console.log(err);
+});
+```
+
+When it replies, you need to extract the `sig` attribute to obtain the relayer's public key
 
 #### Sending transaction details
 
diff --git a/test-dapp/app/components/approveandcallgasrelayed.js b/test-dapp/app/components/approveandcallgasrelayed.js
index 45adee8..6fec346 100644
--- a/test-dapp/app/components/approveandcallgasrelayed.js
+++ b/test-dapp/app/components/approveandcallgasrelayed.js
@@ -117,7 +117,7 @@ class ApproveAndCallGasRelayed extends Component {
                     'contract': this.props.identityAddress,
                     'address': web3.eth.defaultAccount,
                     'action': 'availability',
-                    'token': this.state.gasToken,
+                    'gasToken': this.state.gasToken,
                     'gasPrice': this.state.gasPrice
                 })
             };
diff --git a/test-dapp/app/components/callgasrelayed.js b/test-dapp/app/components/callgasrelayed.js
index a9f639a..c443cce 100644
--- a/test-dapp/app/components/callgasrelayed.js
+++ b/test-dapp/app/components/callgasrelayed.js
@@ -121,7 +121,7 @@ class CallGasRelayed extends Component {
                     'contract': this.props.identityAddress,
                     'address': web3.eth.defaultAccount,
                     'action': 'availability',
-                    'token': this.state.gasToken,
+                    'gasToken': this.state.gasToken,
                     'gasPrice': this.state.gasPrice
                 })
             };
diff --git a/test-dapp/app/components/execute.js b/test-dapp/app/components/execute.js
index 0dd50d6..cdf5ff5 100644
--- a/test-dapp/app/components/execute.js
+++ b/test-dapp/app/components/execute.js
@@ -127,7 +127,7 @@ class Execute extends Component {
                     'contract': SNTController.options.address,
                     'address': accounts[2],
                     'action': 'availability',
-                    'token': STT.options.address,
+                    'gasToken': STT.options.address,
                     'gasPrice': this.state.gasPrice
                 })
             };
diff --git a/test-dapp/app/components/transfersnt.js b/test-dapp/app/components/transfersnt.js
index 0b50550..e3d6abc 100644
--- a/test-dapp/app/components/transfersnt.js
+++ b/test-dapp/app/components/transfersnt.js
@@ -123,7 +123,7 @@ class TransferSNT extends Component {
                     'contract': SNTController.options.address,
                     'address': accounts[2],
                     'action': 'availability',
-                    'token': this.state.gasToken,
+                    'gasToken': this.state.gasToken,
                     'gasPrice': this.state.gasPrice
                 })
             };