Abstract: An improved process for hydrocarbon conversion-catalyst regeneration processes particularly useful for residual oil, especially high carbon content residual oil conversion. The process generally comprises cooling the compressed air which is introduced into the second stage catalyst regeneration vessel in order to allow processing of feeds which typically produce high coke loading of catalyst in the conversion zone. The cooling process described can be installed and maintained with minimal expense in existing facilities and generally comprises a refrigeration unit and a heat exchange means installed in the conduit transporting air from a compressor unit to the second stage catalyst regenerator air distributor means.