Nitrogen-doped zinc oxide (N-doped ZnO) nanocrystallites were synthesized via improved one-step combustion technique by using citric acid as additive. Scan electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to determine the grain size, shape, degree of nitrogen incorporation and nature of the resultant oxynitride chemical bonding. The catalytic performance of N-doped ZnO on the thermal decomposition of ammonium perchlorate (AP) was investigated by DSC-TG technique. The results show that the as-synthesized N-doped ZnO has uniform crystallite size about 20-30nm in diameter and 1.25%wt nitrogen incorporation, which forms into NO bonding region in ZnO crystal lattice. The nitrogen doping is accountable for the significant increase in catalytic activity on the thermal decomposition of AP versus the commercial nanometer ZnO and the thermal decomposition peak shifts 133°C downward when the content of N-doped ZnO in AP is 3%wt.