In this paper, we have studied the effect of LiI and I-2 concentrations on the photovoltaic properties of dye-sensitized solar cells (DSSCs) based on NiO. For all concentrations of iodine, the photo-voltage (V-OC) and current density (J(SC)) increased with increasing LiI concentration. The increment in J(SC) is ascribed to the higher charge transport efficiency of the device. In addition, the effect of NiO film thickness on the efficiency of the as-fabricated DSSCs was investigated, and an optimum efficiency of 0.0587% was obtained for the DSSC with a double-layer NiO film.