Several mixed ZnO-Al2O3 systems were prepared by the impregnation method and calcined for 5 h at 300, 600 and 1000 ° C. The crystal structure, surface acidity, surface basicity, surface area, catalytic decomposition of H2O2 and the electrical conductivity of the samples prepared were studied. It was found that the decomposition of H2O2 is catalysed by the acidic sites formed on the catalyst surface at composition less than 50 mol% ZnO and by basic sites for oxides having composition higher than 50 mol% ZnO. ZnAl2O4-spinel was found to be formed at temperatures ? 600 ° C and it has a catalytic activity and electrical conductivity lower than each of the pure ZnO and the oxide mixtures. The results obtained were correlated together and discussed.