The synthesis of some new cobalt (III) complexes: [Co (5-Xsalen) (PEt3)] ClO4.H2O (where X= H, NO2, Br, OMe) were synthesized and characterized using elemental analysis, 1HNMR, IR and UV-vis spectroscopy. The summarized results of these spectral evidences are in conformity with the structure of the synthesized complexes. In this study, we synthesized four novel complexes of Co (III) by the reaction of the metal ions with the salen ligands. The ligands coordinated with the metal ions through N- and O-donors. The complexes exhibited a geometry based on the coordination number 5. The results showed 1HNMR spectra of these complexes are consistent with the suggest formulation and show that the cobalt in these complexes is low spin. Its structure was established by 1HNMR, IR, and UV-visible spectroscopy.