Purified extracelluar glucoamylase from Arachniotus sp. was used for kinetic and thermodynamic characterization. Thermal inactivation followed first order kinetics. The denaturation/activation energies of enzyme were 57 and 89 kJ mol(-1), respectively. Both enthalpy and entropy of activation for inactivation were lower than those for glucoamylases reported in literature. It is suggested that the enzyme is highly thermostable and is suitable for industrial applications.