A low cost cyanine dye,1,1-dimethyl-3-ethyl-2-[3-(1,3-dihydro-3,3-dimethyl-1-ethyl-5-carboxyl-2H-indol-2-ylidene)-1-propenyl]-1H-benz[e] indolium iodide (1) was synthesized and applied to sensitize mesoporous TiO2 electrode.Photoresponse of the electrode was extended to the visible and remarkably high incident photon-to-current conversion efficiency (IPCE) over 70% was achieved from 500 nm to 600 nm.