Abstract: The acidity and texture of HZSM-5 zeolites (ratio of silica-to-alumina is 38) treated with steam at different temperatures were studied by XRD, NH3-TPD, IR, specific surface area and pore texture determination. The results show that the crystallinity of HZSM-5 zeolites reduces slightly with the increase of treating temperature. NH3-TPD reveals that the acidity decreases remarkably after steam treatment. The weak acid sites increases, while the strong acid sites decreases relatively with the increase of temperature. A definite blue shift in IR wave number was observed when the sample was hydrothermally treated at different temperatures. The surface area and microporous volume decrease, while mesoporous volume increases.