Today, techniques such as TEM, Laser Raman Spectroscopy, EELS,13C NMR, and temperature-programmed oxidation (TPO) are used to study coked catalysts. Probably the most widely used technique is TPO. This Altamira Note discusses the use of TPO coupled with a new detection method developed by Dr. S.C. Fung and Dr. C.A. Querini at Exxon Research and Engineering Company. This method is simple and permits the continuous monitoring of the rate of coke oxidation.