CaO-C catalysts were prepared by precipitating calcium acetate with citric acid for 4 hours in an aqueous solution at 80℃ followed by reduction at 500-700℃. The resultant average pore radius and BET surface area of CaO-C, CaO crystallite size, and CaO dispersion in CaO-C wereabout 15-25 A and 170-200 m²/g, 16.7 nm, and 7.4%, respectively. These values suggest that the highly dispersed CaO-C catalyst formed mainly due to the remained carbon acting as a spacer. The 4 wt% Ni/CaO-C reduced at 700℃ was used for one step synthesis of MIBK from acetone. 60-70% of acetone overall conversion and 70% of MIBK selectivity were obtained which are much higher than those ever reported. The DIBK selectivity was decreased drastically because the remained carbon lowered the basic strength of CaO.