Abstarct: mextallic ferromagnetic laxyers such as Ni, Fe, Co and their alloys are applied widely in manufacturing technology of sensors, magnetic heads and data storage systems. In this thesis, we deposited Cobalt thin films on aluminum, silicon and ITO substrates by Electrodeposition method and their properties were investigated. X-ray diffraction results showed that the films have Hexagonal crystal structure with (002) preferred orientation. The effect of electrolyte temperature on the structural and magnetic properties of thin films of cobalt deposited on aluminum and silicon substrates was studied and increase in saturation magnetization and coercive filed observed by increase in electrolyte temperature for the films on Al substrate. While for films on silicon substrate, decrease in saturation magnetization and increase in coercive field observed by increase electrolyte temperature. The effect of thickness of the films on Al, ITO substrates was also studied on structural and magnetic properties of the films. The results showed that increase in saturation magnetization and residual magnetization of the films for both substrates with the increase in films thickness. The effect of deposition potential on the structural and magnetic properties of the films deposited on the aluminum substrate was investigated. The result of SEM analysis indicated improve in the films surface morphology by increase in deposition potential. Finally the effect of Al substrate thickness on the structural and magnetic properties of the films was studied and the result indicated dependence of structural and magnetic properties on the substrate thickness.