Thermostable amylolytic enzymes are currently investigated to improve industrial processes of starch degradation. Streptosporangium sp. an endophytic actinomycete isolated from leaves of maize (Zea mays L.) showed glucoamylase production, using starch-Czapek medium, and the highest rate was obtained in the initial growth phase, after incubation for 24 h at pH 8.0. Maximum glucoamylase activity (158 U mg(-1) protein) was obtained at pH 4.5 and 70 degreesC. The isolated enzyme exhibited thermostable properties as indicated by retention of 100% of residual activity at 70 degreesC for 30 min with total inhibition at 100 degreesC. Extracellular enzyme from Streptosporangium sp. was purified by fractionated precipitation with ammonium sulphate. After 60% saturation C protein, and yield was 74% with purification 2.7 fold. The enzyme produced by Streptosporangium sp. has produced 421 U mg(-1) potential for industrial applications.