Adsorption equilibria of four nonpolar molecules (benzene, toluene, hexane, and cyclohexane) and two polar molecules (methanol and acetone) on mesoporous silicate MCM-48 were measured at (303.15, 313.15, and 323.15) K using a gravimetric technique. It was found that MCM-48 has a higher affinity to polar organic compounds than to nonpolar organics. A hybrid isotherm model composed of Langmuir isotherm and Sips equations was applied to fit the adsorption equilibrium data of nonpolar organics including surface adsorption and capillary condensation, while inhomogeneous Dubinin-Astakov (DA) isotherm was used to correlate those of polar organics. The proposed isotherms correlated the measured adsorption data well over the whole range at these experimental conditions.