One step synthesis of MIBK from acetone was performed over Ni-CaO catalyst prepared by co-impregnation, where calcium acetate and nickel acetate were selected as catalyst percursors. Overall conversion and MIBK selectivity were 50 ∼ 60 mol% and 30 ∼ 35 mol%, respectively. As the Ni loading increased, the formation of 2-propanol and 4-methyl-2-pentanol, byproducts from hydrogenation, were increased. Even in case of 1∼2 wt% Ni-containing Ni-CaO catalyst, very high catalytic activity was shown, whereas CaO-only-catalyst hardly showed catalytic activity suggesting that added Ni could play a role as promotor as well as hydrogenation active site. Comparing TPR profiles of Ni-CaO before and after reduction with that of CaO, the incorporated Ni was suggested to influence CaCO₃, catalyst precursor, to form readily CaO, active basic component, at even 500 ℃.