This paper reported the use of SnO2 with high surface area improve photocurrent of viologen/Ru-complex in photoelectrochemical cells. The nanocrystalline SnO2 was prepared using the chemical-bath-deposition method. The preparation of Ru(2,2’-bipyridine-4,4’-dicarboxylic acid)2(NCS)2 [(RuL2(NCS)2)]/di-(3-aminopropyl)-viologen (DAPV) in SnO2/tin-doped indium oxide (ITO) is easily prepared using self-assembled monolayers (SAMs). The energy levels of RuL2(NCS)2, DAPV, SnO2, and ITO were well arranged, and the system forms an efficient acceptor-sensitizer. The photocurrent measurement of the systems showed excellent photocurrent of 30 nA/cm2 under the air mass (AM) 1.5 conditions (100 mW/cm2), which was increased by a factor of four compared to ones without tin-oxide layers.