Three different regeneration methods to recover the catalytic activity of spent resid fluid catalytic cracking (RFCC) catalyst were investigated. Carbochlorination method was the most effective to remove contaminant metals from spent equilibrium catalyst (E-cat). However, catalytic activity was not restored due to severe chlorination condition. The attempt to remove Fe, Ni, and V as a volatile corresponding metal carbonyl compound from E-cat was not effective due to low reactivity between contaminant metals and CO. The most effective method to rejuvenate spent E-cat was washing with weak acid after converting metals to a water-soluble form by calcination. Electron probe micro analysis (EPMA) for the cross-sectional profile of Ni, Fe, and V of the regenerated catalyst particle showed that three regeneration methods removed Ni, Fe, and V unifomly throughout the catalyst particle. (C) 2001 Elsevier Science B.V. All rights reserved.