Mahua oil (Madhumica indica) with an iodine value of 88 g/100 g, and containing 46% oleic acid and 12.74% linoleic acid, was epoxidised in situ with hydrogen peroxide as oxygen donor and glacial acetic acid as active oxygen carrier in presence of catalytic amount of an inorganic acid. Catalytic loading of two different acids, i.e., H2SO4 and HNO3 were studied, and H2SO4 was found to be more effective in terms of conversion to oxirane. The effects of various parameters, such as temperature, hydrogen peroxide-to-ethylenic unsaturation mole ratio, acetic acid-to-ethylenic unsaturation mole ratio, and stirring speed, on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidised mahua oil (EMO) were studied. The effects of these parameters on the conversion to the epoxidised oil were studied and the optimum conditions were established. The rate constant and activation energy for epoxidation of MO was found to be of the order of 10(-6) 1 Mol(-1) s(-1) and 14.5 kcal mol(-1), respectively. Thermodynamic parameters such as enthalpy, entropy and free energy of activation were found to be of 13.8 kcal mol(-1), -51.1 cal mol(-1) K-1 and 30.6 kcal mol(-1), respectively. Relative conversion data showed that it was possible to develop epoxides from locally available natural renewable resources such as mahua oil. (c) 2005 Elsevier Ltd. All rights reserved.