Three series of Ru/Al2O3 catalysts were prepared by spray reaction (SPR), impregnation (IMP), and these two methods combined. The characteristics of multi-component SPR particles, as CO2 hydrogenation catalysts, were elucidated. The catalytic activity (TOF) of SPR fine particles was higher by one order of magnitude than that of IMP catalyst without any promoters. This is attributed to the formation of more active species at the perimeters between Ru metal and Al2O3 over SPR particles than over IMP catalysts. The addition of alkaline salts promoted the catalytic activity of Ru/Al2O3, irrespective of preparation methods employed. The promotion of alkali metals to Ru/Al2O3 catalysts is probably due to a synergetic effects including the modification of local electron density on Ru metal by the electron donation of alkali metals, the neutralization of residual chlorine ions by the formation of alkaline chloride, and the removal of depositional inactive carbon by alkaline carbonate catalysis.