The petroleum coke from a fluid coking process was pyrolyzed in helium and oxidized in 1% and 4% O-2 and in air, with the aim to determine N-containing compounds such as HCN, NH3, NO, and N2O. The experiments were performed with and without limestone. NO was the major product during all oxidation runs. N2O was formed only in air. In this case, N2O formation was delayed when compared with that of NO. The addition of limestone decreased formation of HCN and increased that of NH3, whereas NO formation was least affected.