A temperature-programmed reduction study of equilibrium fluid catalytic cracking (FCC) catalysts has shown three hydrogen-consumption peaks associated with contaminanted metals. A low-temperature peak, located near 510degreesC, is produced by the reduction of several components in the catalyst. Highly-dispersed vanadium contributes to this peak. A high-temperature peak, located near 800degreesC, is produced by reduction of nickel aluminate or nickel silicate compounds. A linear relationship exists between the area of the high-temperature peak and nickel concentration on equilibrium catalysts. An intermediate-temperature peak, located near 690degreesC, appears to be related to some form of vanadium compound. The intermediate-temperature peak does not occur on low-vanadium-concentration equilibrium catalysts, but is observed at higher vanadium-contamination levels.