The lipase was partially purified by ion exchange chromatography and gel filtration column chromatography, and was characterized from Geobacillus stearothermophilus AH22 strain. The lipase was purified 18.3-folds with 19.7% recovery. The lipase activity was determined by using p-nitrophenyl esters (C-2-C-12) as substrates. The K-m values of the enzyme for these substrates were found as 0.16, 0.02, 0.19 and 0.55mM, respectively, while V-max values were 0.52, 1.03, 0.72 and 0.15 Umg(-1). The enzyme showed maximum activity at 50 degrees C and between pH 8.0 and 9.0. The enzyme was found to be quite stable at pH range of 4.0-10.0, and thermal stability between 50 and 60 degrees C. It was found that the best inhibitory effect of the enzyme activity was of Hg2+. The inhibitory effect as orlistat, catechin, propyl paraben, p-coumaric acid, 3,4-dihydroxy hydro-cinnamic acid was examined. These results suggest that G. stearothermophilus AH22 lipase presents very suitable properties for industrial applications.