Abstract: Thirteen mould cultures, capable of producing proteases by solid state fermentation, were isolated from soil. Rhizopus oligosporus IHS13 strain was found to be the best producer of acidic proteases. The agricultural by-products namely sunflower meal, wheat bran, soybean meal, lupin cake and cotton seed meal were evaluated as inducers for the production of enzyme. The enzyme synthesis was maximum when sunflower meal was used as substrate. The production of proteases by Rhizopu s oligosporus HIS13 strain was studied by varying the size of inoculum and type of diluent. The optimum inoculum size and diluent were 10% and distilled water, respectively. The effect of different buffers on the extraction of enzyme was also studied and distilled water was found to be the best extractor. The maximum enzyme production, obtained during the course of study was 4.8 U ml-1.