The adsorption of myristic, palmitic and stearic acids on rice hull ash from isooctane as solvent was studied and conformed to a Langmuir isotherm. Monolayer coverage was determined to be 40.08, 38.43 and 37.27 mg/g, respectively. The free energy of adsorption, Delta G(ads)(o), for the adsorption was determined to be -6,25, -6.32 and -6.39 kcal mol(-1) for the adsorbates, respectively. The equilibrium parameter indicated that rice hull ash is a good adsorbent for myristic, palmitic and stearic acids examined.