Full factorial experimental design method was applied for investigation of the effects of different space velocity (SV) (500-1500 mLn/(g-cat.h)) and H-2/CO molar feed ratio (1-2) on CO conversion and/or DME selectivity as the response variables over a physically prepared bifunctional catalyst (CuO/ZnO/Al2O3+ H-ZSM-5) for liquid phase direct DME synthesis from synthesis gas. The results showed that feed composition is the more effective factor on the response and the interaction of the SV and H-2/CO only slightly influenced the response. The factor levels that can maximize the S-DME are SV of 1500 mLn/(g-cat.h) and H-2/CO of 1.5 at 240 degrees C and 35 bar.