Abstarct: Schiff baxses have an important contribution in coordination development. One of the most important and most applications of them, like porphyrins, is the oxygen transfer process, easily patterning cytochrome P-450 enzyme, and they can also functionize normal hydrocarbons and conduct their various reactions. Recently, broad researches have been done around catalytic role of Schiff baxse complexes in order to mimic their enzymic role, and for a better understanding of the biomimetic reactions of cytochrome P-450 enzymes. Most of these researches are related to olefins epoxidation and alkane hydroxylation. Epoxides are useful synthetic intermediates that change to a large scope of useful compounds in pharmacy, agriculture, and industry simply by ring-opening reactions. Epoxidation reactions are usually carried out by an oxygen-donor through the straight transfer of oxygen to alkenes. However, these reactions are so slow and have low efficiency. Schiff baxse transition mextal complexes can be used to catalyze these transformations. In the present thesis, two new catalytic systems have been presented for alkene epoxidation using the five-coordinate Schiff baxse ligand (dha)2dien ¡[N3O2]¡. At first, epoxidation of some alkenes was studied using the homogeneous Schiff baxse catalytic system manganese(III) Schiff baxse and sodium periodate oxidant. In this system, cyclooctene was chosen as basis alkene, and some parameters like solvent, oxygen-donor, and their values were optimized. Then, through covalent binding of the ligand to the chloromethylated polystyrene as support, heterogeneous catalyst manganese(III) schiff baxse was produced. The complex was characterized by spectroscopic techniques. Parameters such as solvent oxidant for cyclooctene were optimized and used in other alkene epoxidations. The new heterogeneous catalyst has catalytic activity and higher yield than the homogeneous one, and also its extraction and recovery from reaction mixture is easily carried out. In addition, recovery experiments showed that repeated times without any loss in catalytic activity are usable.