Tungsten carbide/carbon (WC/C) composite nanofibers were successfully prepared through electrospinning followed by a one-step heat treatment using in-situ carburization. The WC/C nanofibers were applied to low-cost and platinum-free counter electrodes for dye sensitized solar cells (DSSCs), and their catalytic activities were investigated and compared to platinum (Pt) CEs for triiodide/iodide (I₃⁻/I⁻) as well as organic disulfide/thiolate (T₂/T⁻) electrolytes. When WC/C nanofibers are used as the CE catalyst in iodine electrolytes, the DSSCs exhibited a power conversion efficiency (PCE) of 7.77%, corresponding to 96% of that of Pt CEs. In the case of T₂/T⁻ redox couples, the DSSCs based on WC/C nanofibers achieved PCE of 5.85%, which is almost twice that of Pt (3.07%). The high catalytic activities of WC/C nanofibers are attributed to synergetic effects from the combination of catalytically active WC and one …​