The effects of sulfonated surfactants on the adsorption and diffusion of mono azo dye into water-swollen cellulose membranes were studied at 25-55 degreesC. The results were analyzed on the basis of the parallel diffusion theory of surface and pore diffusion. Addition of the surfactants increased the equilibrium adsorption of the dye onto cellulose and the pore diffusivity for the parallel diffusion model. The surface diffusivity for the model was not affected. The temperature dependence of the effects was also discussed.