In the present study, the effect of pH on the adsorption of linear alkylbenzene sulphonate (LABS) by bentonite clay was investigated. Anionic surfactant solutions with initial pH values of 3, 6, 8 and 12 were used. The LABS concentration was determined by UV spectrophotometry, and Fourier Transform-IR was used for clay-LABS interaction. The spectroscopic results indicated that LABS adsorbed on bentonite. The adsorption isotherms were formed. The adsorption of LABS on bentonite was found to correspond with the Freundlich adsorption isotherm, and k and n constants were determined from Freundlich's linear equation. Moreover, the conductivity of suspensions with different concentrations of LABS and pH values was determined, and conductivity of aqueous phase was increased at pHs 3 and 12. From the obtained results, the highest LABS adsorption onto bentonite was determined at low pHs and concentrations.