Production of glucoamylase employing our laboratory isolate, Aspergillus sp. A3 under solid state fermentation was optimized. Different substrates like wheat bran, green gram bran, black gram bran, corn flour, barley flour, jowar flour, maize bran, rice bran and wheat rawa were studied to optimize the best substrate. Wheat bran showed the highest enzyme activity. The physical and chemical parameters were optimized. The maximum enzyme activity under optimum conditions was 247 U/g of wheat bran. The optimum conditions are fructose as additive 1% w/w, urea as additive 1% w/w, incubation time of 120 h, incubation temperature at 30 degreesC, 2:10 (v/w) ratio of salt solution to weight of wheat bran, inoculum level 10% v/v, moisture content of solid substrate 80%, 1:50 ratio of substrate weight to flask volume and pH 5.0. (C) 2002 Published by Elsevier Science Ltd.