LiFe1-yMnyPO4/C nanofiber composites are applied as cathode materials in Li-ion batteries and their electrochemical properties are explored. Nanofiber meshes are synthesized via electrospinning of commercially available precursors (LiOH.H2O, FeSO4.7H2O, MnSO4.H2O, H3PO4, and polyvinylpyrrolidone). Nanofibers calcined at 850 degrees C under Ar/H2 (95/5 vol%) atmosphere are directly used as self-supporting electrodes in Swagelok half cells without the need for any conductive additive or polymer binder. The morphology, phase, and chemical composition of as-prepared and heat-treated samples are analyzed by means of X-ray powder diffraction, thermogravimetric analysis, and electron and scanning microscopy techniques. BrunauerEmmettTeller gas adsorptiondesorption measurements show a high specific surface area (111m2 g-1) for LiFe0.5Mn0.5PO4. The influence of different Fe/Mn ratios on the morphology, electrical, and electrochemical performances are analyzed.