Ah you are right about the "toRadix" I was using it in a way that was wrong but still functioned correctly. It should be replaced with "toNumber()". What that expression is doing is formatting it as will be accepted as a "decimal" and then converting it to a whole number. For NIFI-2950 I am also adding a "fromRadix" function that will convert from one base to base 10. When you tried the expression, did you do it using a latest build off master or a released NiFi version? I just posted a Pull Request (PR) adding proper support for whole number hex values and a fromRadix() function. Please, feel free to test and post feedback on the PR to github. This should allow you to simply do "${'$2':fromRadix(16)}". Here is the link: https://github.com/apache/nifi/pull/1161 ... View more