The kinetic behavior of a commercial γ-Al2O3 catalyst for the methanol to dimethyl ether (DME) dehydration reaction has been investigated using a differential fixed bed reactor at the pressure range 1-16 barg within a temperature range of 260-380 ℃. The experimental runs were performed in a wide range of feed to water ratios. The experiments were designed by general full factorial design (GEFD) and a novel rate equation has been developed which exhibited the best fitting with our experimental data. Based on the analysis of variance (ANOVA), the following order of importance for operating conditions was obtained when the objective function is the yield of DME: Temperature>Water % in feed>Pressure. In addition, the optimum operating conditions for the maximum yield of DME, were found at T=380 ℃, P=16 barg and zero wt% of water in the feed.