Co-doped ZnO nanorods (Co-ZnO NRs) were synthesized by hydrothermal method using cationic surfactant cetyltrimethylammonium bromide (CTAB). Their physical growth mechanism was traced in the light of FESEM and HRTEM studies. A strong correlation between their electronic structural arrangement and photocatalytic activity was established. Broad and uniform peaks were found between 525 and 700 nm in UV-Vis. diffuse reflectance spectra, which were attributed to the d-d transition of Co2+ ion. Successful loading of the nano-sized sensitizer CdS onto the Co-ZnO NRs' surface, contributes to the band gap reduction in CdS/Co-ZnO NRs (Eg = 2.25 eV) sample. X-ray absorption spectroscopy confirms the presence of the lower degree structural disorders in CdS/Co-ZnO NRs with respect to the pristine ZnO and Co-ZnO NRs. Gradual modification in pristine ZnO NRs enhances the photocatalytic activity. Hetero-assembly of 1.5% Pt/CdS/Co-ZnO NRs, exhibited excellent photocatalytic responses in terms of quantum efficiency (1.98%) and hydrogen generation capacity (67.20 mmol/H-2 g) under 1 Sun (1.5AM G) light exposure. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.