The evolution of carbon (C) and nitrogen (N) in a spent (coked) fluid catalytic cracking (FCC) catalyst was investigated during regeneration. A commercial spent FCC catalyst from one refinery was submitted to calcination procedures with air, and samples were collected at different temperatures and times. These were analyzed by X-ray photoelectron spectroscopy (XPS) before and after milling to follow the variation of C and N contents in the surface. It was observed that both C and N are preferably located on the external FCC catalyst surface. For a total C amount of 1.3 wt %, the C content on the surface is about 18.3 wt %. The surface N present in coke is 1.4 wt %, so that the calculated amount of N in the spent catalyst is 176 ppmw. During thermal treatments a simultaneous removal of C and N from the spent catalyst was observed. However, N evolution was slightly slower and completed at a higher temperature than C.