Processes for the reduction of NOx emissions from a regeneration zone during a fluid catalytic cracking of a hydrocarbon feedstock into lower molecular weight components are disclosed. The processes comprise contacting during a fluid catalytic cracking (FCC) process where NOx emissions are released from a regeneration zone of a fluid catalytic cracking unit (FCCU) operating in a heterogeneous combustion mode under FCC conditions, a hydrocarbon feedstock with a circulating inventory of a FCC cracking catalyst and a NOx reduction composition. The NOx reduction composition comprises: (1) at least one reduced nitrogen species component having the ability to reduce the content of reduced nitrogen species to molecular nitrogen under reducing or partial burn FCC conditions and (2) at least one NOx reduction component having the ability to convert NOx to molecular nitrogen under oxidizing or full burn FCC conditions. The reduced nitrogen species and the NOx reduction components do not significantly increase the content of reduced nitrogen species or NOx under any mode of combustion during a FCC process.