Current research reports the synthesis of in-situ TiO2/RGO nanocomposite and used as a heterogeneous catalyst for the transesterification of waste cooking oil into biodiesel. The prepared catalyst was characterized viz. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA) techniques conforming the successful formation of nanocomposite. The effects of various reaction parameters used for transesterification were examined to optimize the reaction conditions. The best operational conditions were oil to methanol molar ratio of 1:12 at 65 degrees C with 1.5 wt% catalyst loading and reaction time of 3 h. The catalyst showed good catalytic activity in biodiesel production and biodiesel conversion of 98% was obtained under optimum reaction conditions. Biodiesel conversion was confirmed by Proton Nuclear Magnetic Resonance (1H NMR), Carbon Nuclear Magnetic Resonance (C-13 NMR) and Gas Chromatography-Mass Spectroscopy (GC-MS) techniques. The excellent catalytic activity of TiO2/RGO could be attributed to the enhanced surface area of the composite. (C) 2018 Elsevier Ltd. All rights reserved.