Abstract: The startup of a fluidized bed process unit uses an air heater to raise the temperature of the unit to the level necessary for operation of the unit to be self-sustaining in its normal operating regime without the use of torch oil. This startup sequence is particularly useful for fluidized bed units which utilize a circulating catalyst with particular emphasis on endothermic conversion units such as FCC and Resid Catalytic Cracking (RCC), but also on other catalytic units with circulating catalyst inventories such as various exothermic conversion, e.g. methanol conversion, processes. Elimination of the torch oil injection enables catalyst selectivity/activity to be retained during startup and at any other time that the heat requirement of the unit cannot be met by the internal functioning of the process, e.g. by coke generation during the reaction and combustion during regeneration of the catalysts or during the reaction itself.