As an alternative to a US buffer layer for Cu(In,Ga)Se-2-based solar cells, we prepared In-based buffer layers using a chemical bath deposition method. XPS and XRD analyses revealed that the In-based buffer layers contained In2S3 and InOOH phases. Compared with US film, the In-based film, In-x(OOH,S)(y), had higher optical transmittance and a shorter absorption edge. The Cu(In,Ga)(Se,S)(2) solar cell with the In-x(OOH,S)(y) buffer layer had better photovoltaic properties than that with a conventional US buffer layer. The conversion efficiency of the best Cu(In,Ga)(Se,S)(2) solar cell with In-x(OOH,S)(y) buffer layer was 12.55% for an active area of 0.19 cm(2).