In order to replace chemical bath deposited (CBD) US buffer layers in Cu(In,Ga)Se-2 (CIGS) solar cells by an alternative material, InxSy thinfilm buffer layers were prepared by ultrasonic spray pyrolysis at various substrate temperatures. X-ray Diffraction measurements confirmed that the films contained primarily the tetragonal In2S3 phase. X-ray Photoelectron Spectroscopy measurements revealed a small concentration of chlorine impurity throughout the InxSy layer. By depositing the indium sulphide layer as buffer layer in the CIGS solar cell configuration, a maximum solar cell efficiency of 8.9% was achieved, whilst the reference cell with CdS/CIGS on a similar absorber exhibited 12.7% efficiency. Additionally, light soaking enhanced the efficiency of InxSy/CIGS cells primarily by improvements in fill factor and open circuit voltage. (C) 2007 Elsevier B.V All rights reserved.