Lipase from Geotrichum candidum was heat inactivated in 0.1M phosphate buffer solution. The thermal inactivation followed first order kinetics for the range of temperatures 50°-80℃ except at 50℃. The changes in enthalpy, entropy and Gibbs free energy at 60℃ were 120.4 kJ/㏖, 73.0 J/㏖·K and 96.9 kJ/㏖ respectively a value of 19℃(Geotrichum candidum lipase) is greater than that of lipases from milk and pancreas. The effect of detergents, lecithin and linoleic acid or the thermal inactivation of lipase was found to be negligible.