The sensitization of dispersed P25 TiO nanoparticles (NPs) and macroporous TiO films with water-soluble and air-stable PbS quantum dots (QDs) capped with l-glutathione (GSH) ligands was investigated. Optimum sensitization was achieved by careful adjustment of the surface charges of TiO and PbS QDs by controlling the pH of the QD solution. Efficient electron transfer from photoexcited PbS QDs via the GSH ligands into the conduction band of TiO was demonstrated by photoluminescence (PL) spectroscopy of PbS-sensitized P25 nanoparticles. The PbS QD-sensitized porous TiO electrodes were used to prepare quantum-dot-sensitized solar cells (QDSSCs) utilizing a CuS counter electrode and aqueous polysulfide electrolyte. Cells with up to 64% injection efficiency, 1.1% AM 1.5 conversion efficiency, and short circuit current density of 7.4 mA cm were obtained. The physical parameters of the cells were investigated using impedance spectroscopy.