A novel aluminum-containing, bimolybdenum-capped Keggin-type polyoxomolybate cluster of the {AlMo12O40(MoO2)(2)} anion has been synthesized and characterized. This is the first experimentally determined Keggin-type {AlMo12O40} polyoxoanion. The polyoxometalate crystal exhibits high selectivity toward the heterogeneous catalytic oxidation of cyclohexanol to cyclohexanone.