In this study, first different SiO 2 /Al 2 O 3 ratios of Al-MCM-41 according to previous reports were synthesized and various amounts of H 3 PO 4 were loaded on Al-MCM-41. These catalysts were used in vapour phase esterification to produce of hexyl acetate and butyl acetate. High conversion and selectivity were obtained. Some techniques such as BET, XRD, Si-MAS-NMR were used for investigating the structural properties of these catalysts. The optimized catalyst was selected .The operational factors such as reaction temperature, molar ratio of reactants, SiO 2 /Al 2 O 3 ratio of catalyst, % H 3 PO 4 , feed flow rate were examined. Finally, the catalytic efficiency of each catalyst was tested for 18h. The results showed that 30 % H 3 PO 4 /Al-MCM-41(70) was more active than the other catalyst for esterification of acetic acid with 1-hexanol and Al-MCM-41(150) showed the best results for esterification of acetic acid with 1-butanol. The hydrophobic properties, total acidity of catalyst and length of alkyl group were suggested to play important roles in the conversion and selectivity.