A series of Ru/Y-zeolite catalysts with various alkali and alkaline earth neutralizing cations in zeolites was prepared. These neutralizing cations did not show significant influence on hydrogen chemisorption. However, the turnover frequencies (TOF) of Ru in the CO/H2 reaction is enhanced when the neutralizing Na cations are replaced by alkaline earth cations. This effect can be attributed to an increase in electron deficiency of the metal crystallites due to the higher acid strength of alkaline earth-Y zeolites. Significant amounts of isobutane were found in the product stream. This is due to the bifunctional mechanisms of the catalysts.