A process is described for converting synthesis gas containing carbon monoxide and hydrogen to hydrocarbons via methanol as an intermediate, by contacting the synthesis gas with a catalyst system containing a mixture of gallium silicate zeolite catalyst and a methanol catalyst. The process results in reduced amounts of undesirable low carbon number hydrocarbons, e.g., C4 and lower, undesirable high carbon number hydrocarbons, e.g., C10 and higher, and aromatic hydrocarbons. The process provides higher yields of useful, high octane hydrocarbons boiling in the gasoline range.