The effect of the viscosity of room temperature molten salt (RTMS) electrolyte has been investigated on the performance of dye-sensitized solar cell (DSSC). Both the short circuit photocurrent and conversion efficiency are increased with decreasing the viscosity of RTMS as in the case of conventional electrolytes. The conversion efficiency of 2.1% observed for the cell of EMIm-F.2.3HF is the highest value reported for all the DSSC consisted of RTMS.