We have collected data on the emissions of NO, HCN, and N-2 during the regeneration of spent fluid catalytic cracking catalyst in two different laboratory-scale units, We have developed a model that describes how coke nitrogen is converted into gas-phase nitrogen-containing species during catalyst regeneration. In this model, the combustion of coke causes the volatilization of nitrogen as HCN, which then can be oxidized to NO or hydrolyzed to NH3. In the presence of coke, NO can be reduced to N-2; this reaction is accelerated by the presence of CO. Our model accurately describes the main elements of the collected emissions data.