Chitosan membranes, cross-linked in sulphuric acid, were evaluated for methanol permeability at high to medium methanol concentrations and compared to the methanol permeability in Nation 117 membranes. As a natural polymer, Chitosan is considered to be a cheap source of membrane material compared to Nafion. Methanol permeability through Chitosan membranes of medium molecular weight for methanol concentration of 12 mol/L at 20degreesC was found to be (8.0 +/- 0.5) x 10(-7) cm(2)/S. This is almost three times lower than the permeability found for Nafion 117 of (2.3 +/- 0.2) x 10(-6) cm(2)/s at the same methanol concentration and temperature. An increased methanol concentration of 18.5 mol/L resulted in a decreased methanol permeability of (5.2 +/- 0.6) x 10(-7) cm(2)/s at 20degreesC for Chitosan compared to increased methanol permeability of (2.7 +/- 0.5) x 10(-6) cm(2)/s at the same temperature for Nafion 117. An increased temperature of 50degreesC at methanol concentration of 12 mol/L however resulted in an order of magnitude increase in methanol permeability ((4.1 +/- 0.3) x 10(-6) cm(2)/S) for Chitosan membrane, which is comparable to the increase in methanol permeability of (3.8 +/- 0.8) x 10-6 cm(2)/S for Nafion 117 membrane. (C) 2004 Elsevier B.V. All rights reserved.