Biohydrometallurgical leaching of iron sulphide ore in an aerobic batch system using bacteria Thiobacillus ferrooxidans has been studied for process parameters optimization. The maximum bioleaching of Fe2+ is 79.88 and 79.10 per cent (w/w) for 25 and 30 kg/m(3) initial ferrous iron loading at optimum conditions. The optimum parameters are-time 172 It, pH 2.5 and temperature 35degreesC. The optimum glucose and nitrogen (as ammonium sulphate) concentration for maximum bacterial bioleaching is 3.0 and 0.30 per cent (w/w) respectively. The optimum shaking speed (rpm) is 60. 20 percent (v/v) and 7 days age-old suspension culture was used for the studies. The bacteria can tolerate up to 35 kg/m(3) initial ferrous iron concentration.