The electrochemical behavior of a series of composites synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time is systematically compared (using cyclic voltammetric and electrochemical impedance spectroscopic analyses). Structural and morphological characterizations of the composites were undertaken using power X-ray diffraction (XRD), N2 adsorption/desorption isotherms and transmission electron microscopy (TEM). The results indicated that the binary nickel/manganese compounds of the Ni–Mn/ordered mesoporous carbon (OMC) composite had a synergistic effect of both components.