Industrialization in the world increased the pollution levels in the environment making life more complicated. General awareness about pollution is increasing today. To control pollution levels, biological methods are eco-safe and economical. In this study a wild strain of Bacillus species was isolated and optimized for bioremediation of ammonia in flask cultures. The study was attempted to develop a process for ammonia bioremediation in a single stage aerobic nitrification and denitrification of ammonia. The results reveal that the optimum pH for the isolated Bacillus species strain was 8 and optimum temperature was 300C. At optimum pH and temperature this organism was able to remove 72.7% of ammonia in flask cultures supplemented with 860 mg l-1 of ammonia. The study on ammonia toxicity revealed that toxicity was due to increase in hydrogen ion concentration and osmosis.