ZnO thin films, showing nano-ridges at the surface and the top layer embedded with metal (Ag/Au) nanoparticles (MNP), were obtained by sol-gel synthesis, using zinc acetate dihydrate [(CH3 center dot COO)(2)Zn center dot 2H(2)O] as precursor. The method involved prior synthesis of Ag and Au nanoparticles via biological reduction of AgNO3 and HAuCl4, respectively, using algae Spirulina platensis. The XRD analysis indicated dominant evolution of wurtzite ZnO phase. Low-angle shift in peaks, seen with nanoparticles embedded films, indicated partial diffusion of metals into ZnO lattice. Band gap energy was least affected and lied in the expected range. AFM and SEM analysis revealed the surface topography and morphology, while EDX analysis confirmed the elemental stoichiometry and existence of Ag/Au nanoparticles in samples. Significant gain in photoelectrochemical current using MNP embedded films is largely accountable to the improvement in electrical conductance and the role played by metal nanoparticles in charge-carrier separation, collection and transport. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.