To disperse nano-sized gamma-alumina powders in non-polar solvents, the surface of gamma-alumina has to be modified with unsaturated oleic acid, which forms aluminum-oleate on the surface. This changes the surface characteristics of gamma-alumina powders from hydrophilic to hydrophobic in nature. A colloidally stable gamma-alumina non-polar suspension is obtained when a critical amount of aluminum-oleate compound is formed on the surface. This is also evidenced by the results of adsorption and theoretical calculation of potential energies, which confirm the colloidal stability of organic gamma-alumina suspension caused by the steric repulsion mechanism.