Platinum is the most commonly used dye-sensitized solar cell (DSSC) counter electrode (CE) due to its superior electrocatalytic activity and high transparency. However, the scarcity and high-cost of Pt restrict its practical application for the large-scale production of DSSCs. Herein, a facile approach for fabricating highly dispersed Co9S8 nanoparticles with small diameters in the range of 5-10 nm on the surface of carbon nanofibers (CNFs) via an electrospinning followed by calcination and hydrothermal reaction was developed. The composite material could be used as an efficient and low-cost Pt-free CE for DSSCs. The DSSC assembled with the prepared Co9S8/CNFs composite as a CE exhibited excellent electrocatalytic activity and a power conversion efficiency (PCE) of 8.37%, which is comparable to that of the DSSC with conventional thermally deposited Pt as the CE (8.50%). Therefore, the Co9S8/CNFs composite can be used as an efficient and low-cost promising alternative CE in DSSCs. (C) 2018 Elsevier Inc. All rights reserved.