This invention is directed to a method and apparatus for regenerating a catalyst used in an FCC unit, including providing a spent catalyst into an upper portion of a regenerator, maintaining a calcination phase, a gasification phase, and a combustion phase of fluidized catalyst in the regenerator, combusting carbon in the combustion phase and producing a combustion flue gas, reacting carbon in the gasification phase with the combustion flue gas to form a carbon monoxide rich flue gas, and calcining the spent catalyst with the carbon monoxide rich flue gas.