Alkene epoxidation is a very useful reaction in industrial organic synthesis. Epoxides are key raw materials for a wide variety of products and much effort is devoted to the development of new active and selective epoxidation catalysts for processes that avoid the formation of large amounts of by-products. There has been an increasing interest over the last years for the development of heterogeneous catalysts for oxidation reactions in the liquid phase with aqueous H 2 O 2 or organic hydroperoxides. This was partially achieved by using transition metal containing zeolites or aluminophosphates which proved to be remarkable catalysts for the oxidation of a large family of small organic molecules with both H 2 O 2 and tert-butyl hydroperoxide TBHP. However, as far as microporous molecular sieves are concerned, reactions are limited to substrates capable of entering the zeolite pores, with a kinetic diameter smaller than 7A° Moreover, these materials are often expensive and relatively difficult to synthesize, as their preparation requires specific conditions to prevent the formation of metal oxide species during the crystallization process. The activity of these catalysts in oxidation reactions has been attributed to the presence of isolated metal sites in a silica or aluminophosphate framework. Because of these limitations due to the presence of micropores, many attempts have been made to replace these zeolite based catalysts by systems containing highly dispersed transition metal cations on various organic or inorganic supports with high surface areas. In this work, we have investigated the catalytic activity of the new synthesized catalyst based on SiO 2 /Al 2 O 3 mixed oxid, in some cycloalkene epoxidation. SiO 2 /Al 2 O 3 was prepared by a sol-gel method with a 1:1 molar ratio of Si in to Al. After this DCDMS was added to the mixed oxide and THF as a solvent. In the next stage, PHTBB was added dropwise to modified it on the mixed oxide and we used DETA for synthesis a Schiff base and for complete the systhesis of ligand, we added SA to the solution.We have investigated all of this stages with FTIR and UV spectra.. For synthesis a new catalyst to cycloalkene epoxidation we mixed the sysnthesized ligand and Co(CH 3 COO) 2 ·4H 2 0 in methanol as a solvent. The sol was stirred for 24h at room temperature. We also sysnthesized a Mn complex at the same methode. The surface area, porevolume and poresize distribution were carried out bye BET method. The catalytic studies were carried out using cyclohexene,? pinen, and cyclooctene as the substrate and TBHP as a oxidant. The reaction mixture was stirred at reflax temperature for 24h in cyclohexan as a solvent.The catalyst was separated and products were identified by GC-Mass.