Water electrolysis is a promising technology for high purity hydrogen production. Among the various hydrogen generation methods, hydrogen production by alkaline water electrolysis offers advantages such as: high durability and capability to employ non-precise metals as the electrode materials. Anodic energy drop in alkaline water electrolyzers is related to slow kinetic of oxygen evolution reaction and high overpotential at the anode side. To overcome this problem, it is necessary to develop the efficient electrocatalysts. Although noble metal oxides show the highest electrocatalytic activity in the oxygen evolution reaction, but non-precious transition metal oxides are applicable in alkaline water electrolysis due to their high stability in alkaline media. In the recent years, cobalt-based electrodes have been extensively investigated as the anode electrocatalyst materials. In this thesis, oxygen electrode was prepared based on the Cobalt nano-rods supported on the modified graphene sheets. Because of the synergistic effect of the graphene and cobalt nano-rods, the hybrid of the cobalt nano-rods and modified graphene (G-NH 2 ) showed an efficient electrochemical activity and high stability for oxygen evolution reaction in alkaline media. The structural and morphological characteristics of the synthesized samples were studied by different methods such as Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy and Thermogravimetric analysis. The electrochemical activity of the electrocatalyst in oxygen evolution reaction was investigated using cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV) techniques. Finally the performance of synthesized sample was investigated as the anode electrocatalyst in an alkaline water electrolyzer single cell. The prepared electrocatalyst improved the electrolysis cell performance by decreasing the anodic overpotential. This electrocatalyst (cobalt hydroxycarbonate nanorods/G-NH 2 ) showed an overpotential of 344.4 mV in the current density of 10 mA cm -2 . Also, by employing this electrocatalyst on a stainless steel mesh, the cell efficiency was increased from 67.45 to 74.2% at 40 ° C, and from 70.9 to 82.7% at 60 ° C.