The adsorption measurements of casein onto alkali treated bentonite were performed at room temperature and fixed pH (11.8) with an object to study the mode of casein adsorption at the alkali treated bentonite surfaces. The adsorption isotherm was found to have a Langmuir nature. The adsorption was pH dependent and increased with a decrease in temperature. The adsorption was quite sensitive to the presence of Cl-, SO42-, and PO43- ions and showed many interesting variations with increasing concentrations of the added anions. Various kinetic and adsorption parameters such as the adsorption coefficient, rate constants for adsorption and desorption, diffusion constant, and penetration rate constant were calculated.