Abstract: The γ-alumina catalyst for the dehydration of methanol to dimethyl ether was synthesized by sol-gel method using aluminum iso-propoxide (AIP) as precursor and 2-propanol (IPA) as solvent. The preparation conditions (n(H2O)/n(AIP) and pH value of solution) were varied to study their effects on phase formation, surface area, pore size distribution and number of acidity sites on the γ-alumina, respectively. The X-ray diffraction revealed that well-crystallized pure γ-Al2O3 can be obtained by varying either (n(H2O)/n(AIP)) or pH of solution. The result from temperature programmed desorption of ammonia (NH3-TPD) of the samples demonstrated the catalyst prepared at n(H2O)/n(AIP)=4.5 and pH=9 showed the most acidic sites and high catalytic activity in the reaction of methanol dehydration.