The present study investigates the sorption and diffusion of water and alcohols in chitosan-acetic acid complex membranes and chitosan-metal ion complex membranes. Chitosan was prepared from chitin abstracted from the crab shell and subsequently deacetylated with NaOH solution. Chitosan was dissolved in an aqueous acetic acid solution and cast into a membrane to form a chitosan-acetic acid complex membrane with varying NaOH treatment time. For these membranes we measured absorption of water, methanol, ethanol, isopropanol and propanol in the complex membrane. From the plots of absorption of solvents as a function of square root of time, diffusion coefficients were calculated. As an alkali treating time is prolonged, membrane becomes more crystalline and thus an equilibrium sorption value decreases. We observed the decreased equilibrium sorption and diffusion coefficient of lower alcohols in the order of methanol, ethanol, isopropanol and propanol resulting from their increased molar volume and decreased heat of vaporization. Sorption and diffusion behavior in chitosan with inserted metal ions such as Mg^{+ +}, Cu^{+ +}, Ni^{+ +}, Co^{+ +}, Fe^{+ +}, Ba^{+ +} and Al^{+ + +}was investigated. Results of this study conclude that the water selectivity in alcohol-water mixture could be enhanced by ion implantation in chitosan membranes.