Ammonia is a potential alternative fuel that was indeed put into use in Belgium in World War II due to the extreme shortage of diesel. It has a high heating value per unit volume (1.16 × 107 kJ/m3) and its combustion products can be as or more environment-friendly compared to conventional hydrocarbon fuels. This study examined the combustion characteristics of premixed ammonia-air mixtures at atmospheric and elevated conditions which are encountered in SI engine operation. The laminar burning velocity, flame temperature and species distribution were determined using the Lindstedt mechanism in CHEMKIN. A freely propagating flame was assumed to facilitate the investigation. The predicted laminar burning velocity and the flammability limits were compared with experimental values.