In this study, we investigate the effect of Co2+ ion incorporation into CdS layer on the photovoltaic performance of quantum dot sensitized solar cell (QDSSC). Quantum dots are deposited by the successive ionic layer adsorption and reaction (SILAR) method on the mesoporous TiO2 film. The doped system modifies the structure of photoanode that leads to an increase in short circuit current density (J(sc)) from 13.16 mA cm(-2) to 16.6 mA cm(-2) in the un-doped system. Electrochemical impedance analysis (EIS) reveals a decrease in charge transfer resistance at the TiO2/QDs/electrolyte interface that arises from the presence of an internal recombination pathway. The highest energy conversion efficiency (eta) of 3.16% is obtained under standard air mass 1.5 global (AM 1.5G) simulated sun light by doping the optimized amount of Co2+ ion in CdS nanoparticles, corresponding to efficiency increment (35%) compared to the un-doped system. The origin of the increase in the efficiency is attributed to the dominance of charge collection to recombination. To further investigation of the electron transport time in the photoanode, the intensity modulated photocurrent spectroscopy (IMPS) is performed under standard conditions. Our obtained results can help to develop a simple and effective method to enhance the efficiency in the QDSSCs. (C) 2015 Elsevier B.V. All rights reserved.