diff --git a/src/main/java/com/xero/api/ApiClient.java b/src/main/java/com/xero/api/ApiClient.java
index 04fa65fd..7545247f 100644
--- a/src/main/java/com/xero/api/ApiClient.java
+++ b/src/main/java/com/xero/api/ApiClient.java
@@ -32,6 +32,7 @@
 import com.auth0.jwt.interfaces.DecodedJWT;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.security.interfaces.RSAPublicKey;
 
@@ -216,7 +217,7 @@ public HttpResponse revoke(String clientId, String clientSecret, String refreshT
 	    headers.setBasicAuthentication(clientId, clientSecret);
 		
 	    // POST BODY WITH REFRESH TOKEN
-		String urlParameters  = "token=" + refreshToken;
+		String urlParameters  = "token=" + URLEncoder.encode(refreshToken, StandardCharsets.UTF_8.name());
 		byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
 		HttpContent content = new ByteArrayContent("application/x-www-form-urlencoded", postData);
 	
diff --git a/src/test/java/com/xero/api/ApiClientTest.java b/src/test/java/com/xero/api/ApiClientTest.java
new file mode 100644
index 00000000..e1bc855b
--- /dev/null
+++ b/src/test/java/com/xero/api/ApiClientTest.java
@@ -0,0 +1,55 @@
+package com.xero.api;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import com.google.api.client.http.GenericUrl;
+import com.google.api.client.http.HttpContent;
+import com.google.api.client.http.HttpHeaders;
+import com.google.api.client.http.HttpMethods;
+import com.google.api.client.http.HttpRequest;
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpResponse;
+import com.google.api.client.http.HttpTransport;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+
+public class ApiClientTest {
+
+    @Test
+    public void revokeFormEncodesRefreshToken() throws IOException {
+        HttpTransport transport = mock(HttpTransport.class);
+        HttpRequestFactory requestFactory = mock(HttpRequestFactory.class);
+        HttpRequest request = mock(HttpRequest.class);
+        HttpResponse response = mock(HttpResponse.class);
+        ArgumentCaptor<HttpContent> contentCaptor = ArgumentCaptor.forClass(HttpContent.class);
+
+        when(transport.createRequestFactory()).thenReturn(requestFactory);
+        when(requestFactory.buildRequest(
+            eq(HttpMethods.POST), any(GenericUrl.class), contentCaptor.capture()
+        )).thenReturn(request);
+        when(request.setHeaders(any(HttpHeaders.class))).thenReturn(request);
+        when(request.setConnectTimeout(anyInt())).thenReturn(request);
+        when(request.setReadTimeout(anyInt())).thenReturn(request);
+        when(request.execute()).thenReturn(response);
+
+        ApiClient apiClient = new ApiClient(null, transport, null, null, null);
+        apiClient.revoke("client-id", "client-secret", "refresh+token&part=value");
+
+        ByteArrayOutputStream requestBody = new ByteArrayOutputStream();
+        contentCaptor.getValue().writeTo(requestBody);
+
+        assertThat(
+            requestBody.toString(StandardCharsets.UTF_8.name()),
+            is("token=refresh%2Btoken%26part%3Dvalue")
+        );
+    }
+}