Potential new electrolytes for dye-sensitized nanocrystalline solar cells (DNSCs) of Gratzel type based on trialkylsulfonium iodides have been investigated. Room temperature molten salts of (Et2MeS)I, (Bu2MeS)I, and (Bu2EtS)I, with iodine in low concentrations, revealed good conducting abilities. DNSCs using iodine-doped (Bu2MeS)l as electrolyte achieved an overall light-to-electricity conversion efficiency of 3.7% in simulated AM 1.5 solar light at a light intensity of 0.1 Sun. The effects from varying the temperature during the IN measurements were studied, as well as the effects of 4-tert-butylpyridine treatment of the electrodes.