Non-photocatalytic water splitting by oxygen-deficient, mesoporous metal oxide-engineering-based hydroelectric cell (HEC) as a path-breaking invention to generate electricity is a well-known phenomenon. To obtain more electricity from HEC, the metal oxide with higher oxygen deficiency is a better option; therefore, use of CeO2 would be a better choice in the present work. Oxygen-deficient mesoporous CeO2, CeO2-rG1, and CeO2-rG2 nanocomposites have been synthesized by the one-step wet precipitation method. Increase in oxygen vacancies in the presence of Ce3+ concentration by the intense F-2g peak in Raman spectra of CeO2-rGO nanocomposite is compared to CeO2. The strain developed in the CeO2 lattice because of defect creation has been verified by high-resolution transmission electron microscopy images and X-ray diffraction. Defect pair formation in nanocomposite emits visible emission were taken by photoluminescence spectroscopy. Addition of rGO in CeO2 improved the surface area from 60.57 to 74.49 m(2)/g, which is confirmed by Brunauer-Emmett-Teller measurements. In HEC, water molecules are chemidissociated on the oxygen-deficient mesoporous surface of the pellet followed by physidissociation of water molecules at mesopores. Current is produced by redox reaction of dissociated ions at the Zn anode and Ag cathode attached to the nanocomposite pellet. Nanocomposite CeO2-rG(2)-based HEC delivers a short circuit current of 21.3 mA and an open-cell voltage of 0.84 V by adding few drops of water. CeO2-rG(2)-based HEC of an area of 4.8 cm(2) delivers a maximum power of 17.66 mW which is 2.25 times higher than the reported power of 7.84 mW for Li-magnesium ferrite-based HEC. Addition of rGO in highly resistive CeO2 significantly enhanced oxygen vacancies and mesoporosity, which improved the output power of HEC.