Abstract: The AlPO₄-5, AlPO₄-11 and AlPO₄-20 molecular sieves have been synthesized hydrothermally in the presence of organic amines or quaternary ammowum which acts as templcte. These samples were characterized by X-ray diffraction patterns and infrared spectra. It was found that the framework topology of AlPO₄-11 is changed after calcinations. DTAshows no structural collapse below -950℃.The adsorption properties of water and hydrocarbons on the samples were studied. The results show that the water pore volumes are greater than the hydrocarbon pore volumes, reflecting the presence of additional pore volume accessible to H₂Obut not to hydrocarbons.