The effect of SiO2/Al2O3 mole ratios (silicate module), as well as thermal and thermosteam treatment on catalytical properties of zeolites HZSM-5 and H-Beta in the reaction of vapor phase esterification of acetic acid by isobutyl alcohol at 140–2000С has been studied. It has been determined that with the increase of silicate modules of zeolites from 30 up to 80 and preliminary thermal and thermosteam treatment of HZSM-5 and H-Beta samples, the selectivity of process and the yield of isobutylacetate grow and the amount of by products such as isobutylene and ester decrease.