The rate processes for the adsorption of Basic Yellow 24 dye on activated sludge biomass have been studied. Influences of various factors on adsorption rate, such as shaking rate, initial dye concentration, biomass particle size, and dye solution temperature have been investigated. The experimental results indicate that there is a boundary layer surrounding the biomass particles, the kinetics of the adsorption process is mainly controlled by intraparticle diffusion. The activation energy for the same process was 1.45 kcal mol - 1 .