A beta zeolite sample (Si/Al = 30) was modified by citric acid, tartaric acid, and hydrochloric acid. The catalytic performances of these zeolite together with another beta zeolite (Si/Al = 12.5) were tested in the anisole acetylation in a fixed-bed configuration. The zeolites were characterized by powder X-ray diffraction, FT-IR of adsorbed pyridine, and temperature programmed desorption of ammonia. The ratios of Si/Al, the specific surface areas, and the pore sizes were also measured. The results showed that the most active and stable behavior was achieved on the HCl treated zeolite. The strong acid sites as many as possible but with an appropriate concentration and strength were needed in order to obtain an optimum activity and stability.