Hybrid materials containing single atoms or molecule-based active species immobilized on nanomaterials have been suggested as new, efficient catalytic systems for various reactions. In this study, novel hybrid materials consisting of molecularly dispersed Ni-based species on a graphitic carbon nitride (g-C3N4) framework are prepared, and their excellent electrocatalytic performance for the oxygen evolution reaction (OER) is discussed. Extensive chemical and structural characterizations confirm that the Ni-based species are attached and well-dispersed on the C3N4 network without agglomeration. In addition, results obtained from electrochemical characterization suggest that Ni-containing molecular entities dispersed on the C3N4 network are active species for the OER.