This work provides further insight on the long term stability, of Dye Sensitized Solar Cells (DSCs) assessed through prolong thermal aging at 85°C in dark. The investigation is focused on Bis(isothiocyanato)(4,4′-dicarboxylato-2,2′- bipyridine)(4,4′-dinonyl-2,2′-bipyridine)ruthenium(II) (Z907) sensitized devices employing commercially available ionic liquid electrolyte (livion 12, L12) with high boiling point. The electrical performance (measured under 1 Sun irradiation condition) of the investigated device Z907/L12 degrades with a rate of −7.58×10−5/hours. The reported results are undoubtedly interesting in the optic of a feasible commercialization for DSCs technology.