Cu2ZnSnS4 (CZTS) thin film solar cells were fabricated on 100 mu m thick flexible glass (FG) substrates coated with Molybdenum (Mo) anodes. The CZTS thin films were deposited by using magnetron sputtering followed by annealing in sulfur vapor. The fabricated cell structure was FG/Mo/CZTS/CdS/ZnO/ITO/Ag, where cadmium sulfide (CdS), zinc oxide (ZnO), tin-doped indium oxide (ITO) and silver (Ag) were used as an n-type window layer, resistive layer, transparent conductor and finger electrode, respectively. The best conversion efficiency achieved of the flexible CZTS solar cell was 3.08%, with an active area of 0.45 cm(2). The conversion efficiency was reduced by 20% when the cell was bent to a 50 mm radius. (C) 2014 Elsevier B.V. All rights reserved.