This paper presents the results of vapour permeation of acetone and isopropanol through a commercially available 'Membralox' membrane with pore diameter of 4 nm at three temperature levels : 160, 180 and 200 degrees C. Three main mechanisms involved in the vapour permeation are Knudsen diffusion, viscous bulk flow and surface diffusion. The expression of the first two mechanisms, taking into account the blockage due to adsorption of an organic vapour on membrane pore wail, was developed before. Two surface diffusion models, namely, Fick's law and HIO. (Higashi, Ito and Oishi) models, were considered. Results from pure component permeation studies were fitted with the models and the validity of the models were checked with experimental results of mixture between the organic vapour and nitrogen gas : The study was further extended to the case of mixtures of acetone and isopropanol vapours;A model was modified to describe the results.