The characteristics of pure MgO, Al2O3 and three binary mixtures of MgO-Al2O3 were studied by determining their BET surface areas, micropore surface area, total pore volume, adsorption-desorption isotherms, the X-ray diffractogram, surface acidity and catalytic functionality for cumene cracking. The XRD results show that the incorporation of alumina into the magnesia beyond 50% renders it amorphous. Furthermore, the mixed oxide containing 50% magnesia and 50% alumina had the highest BET surface area of 200 m(2)/g and is the only mixed oxide with bimodal pores. The results of the acidity measurements and cumene cracking functionality indicates that strong acid sites are found only in mixed oxides containing more than 50% alumina.