Gamma-alumina fine particles were synthesized by sol-gel process. Aluminum tri-sec-butoxide (ATB), anhydrous ethyl alcohol (EtOH), water (H 2 O) and hydrochloric acid (HCl) were used as starting materials. Different samples were synthesized with EtOH/ATB = 60/1, HCl/ATB = 0.08/1 and H 2 O/ATB = 1/1 ratios and calcined at different temperatures. Molar ratios of H 2 O/ATB (from 1 to 25) and HCl/ATB (from 0.08 to 0.4) were changed for some other samples, during the synthesizing process. The products were characterized by both XRD and FTIR measurements. Studies were carried out on the effect of calcination temperature and change of H 2 O/ATB and HCl/ATB ratios on structure and processes involved in phase transformations.