Abstarct: Hetero-polyanions are anionic mextal oxide clusters with the general formula of [XxMmOy]q- (x≦m) in which M is usually tungsten or molybdenum. Polyoxomextalates of the Keggin-type have been known for over 150 years. Bulk HPA as catalysts have low stability and surface area (1–10 m2/g). To improve these characteristics of the HPAs, they are usually supported on a suitable carrier that not only increases its thermal stability and available surface area but also improves its catalytic activity . Impregnation and adsorption which usually used for supporting HPAs on different carriers also suffers from gradual leaching of HPAs from the surface. So in this work, we have been tried to support HPAs to the surface of polyaniline via ionic lixnkage. Polyaniline (PANI) is one of the oldest artificial conductive polymers that its high electrical conductivity has attracted a lot of attention. Easy synthesis and high surface area are its other features that can be noted. The prepared catalysts were characterized by, TGA, UV-Vis spectroscopy, FT-IR spectroscopy, ICP and EDX analysis. Epoxides (oxiranes) are three-membered cyclic ethers that are prepared from alkenes by reaction with different peroxides and peracids. The catalytic epoxidation of alkenes is an important reaction in chemical industry since epoxides are versatile and important intermediates in the synthesis of fine chemicals and pharmaceuticals. The use of heterogenic catalyst could be improved separation process of catalyst which is very important especially for the pharmaceutical materials. In this work we have been used the epoxidation of cyclooctene as a model reaction with prepared catalysts. The various parameters such as type of solvent, type of oxidant, amount of oxidant and amount of catalyst were optimized for this reaction. The progress of these reactions was analyzed using gas chromatography (GC) during 30-180 minutes.