The heat of adsorption was determined from isotherm parameters, which in turn were calculated by Frendlich equation. The method was applied for the determination of adsorption heat of p-nitrophenol, p-nitroaniline and 2,4-dinitrophenol on TW-2 and CAL 12× 40 activated carbons. With the approach, it is easily to cover the influence of the whole range of surface loading on the heat of adsorption, especialy in low surface coverage.