Polycrystalline MgAl2O4 spinel with high purity and stoichiometric composition was prepared using alkoxide precursors. The average grain size of the polycrystal was fine (1.7 mu m). The deformation mechanism of the polycrystal was investigated in air at temperatures of 1300 degrees-1400 degrees C. At 1300 degrees C, oxygen lattice diffusion controlled the deformation, despite the fine grain size; however, increases in the temperature and applied stress caused cavities to nucleate and grow. Spinel possessed better creep resistance than alumina of comparative grain size. The effective diffusion coefficient,vas determined as follows: D-eff(m(2)/s) = 1.9 x 10(-1) exp(- (421+/-26 kJ/mol)/(RT)).