diff --git a/ChangeLog.txt b/ChangeLog.txt
index 6fbc459749870bf5bc6c8d0350ba429468b2a9a2..f6eb685df3c7ac43b83f427fb6d39f68bd64f3f8 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -33,6 +33,8 @@ v1.6.0 - 2021-xx-xx
   Closes #520.
 - Experimental support for Websockets continuation frames. Closes #500.
   Closes #89.
+- `Properties.json()` now converts Correlation Data bytes() objects to hex.
+  Closes #555.
 
 
 v1.5.1 - 2020-09-22
diff --git a/src/paho/mqtt/properties.py b/src/paho/mqtt/properties.py
index f0c50af8ecf48a47fe77b06abb4219c89eccb908..5cfcdb0ccb2920d290793e964a54e2ee67fc75b5 100644
--- a/src/paho/mqtt/properties.py
+++ b/src/paho/mqtt/properties.py
@@ -319,7 +319,11 @@ class Properties(object):
         for name in self.names.keys():
             compressedName = name.replace(' ', '')
             if hasattr(self, compressedName):
-                data[compressedName] = getattr(self, compressedName)
+                val = getattr(self, compressedName)
+                if compressedName == 'CorrelationData' and isinstance(val, bytes):
+                    data[compressedName] = val.hex()
+                else:
+                    data[compressedName] = val
         return data
 
     def isEmpty(self):