Tin oxide (SnO₂) is a well-known material that has been applied widely in various fields, such as catalyst, solar cell and gas sensor. As electrode material, its high selectivity through formate during carbon dioxide reduction reaction (CO₂RR) make it attractive to be explored further. In addition, it is found that compare to a pure substance, composite material exhibits better performance due to the enhanced inner electric field at the particle interface. Zinc oxide (ZnO) becomes one of the promising candidates as a composite material with tin oxide due to low cost, suitability, good chemical stability, and electrochemical properties as well as its selectivity to formate. A wide range of metal oxide have been synthesized by various physical and chemical techniques. Among the techniques, electrospinning is one of the promising and versatile method to create one-dimensional nanostructures such as nanofiber, nanotubes, and nanowires with tunable diameters size and morphology. The high surface to volume ratio can provide large surface areas and also able to reduce mechanical strains within particle thus can increase the performance. SnO₂-ZnO composite hollow nanofibers were synthesized by electrospinning followed by annealing using SnCl₂.2H₂O and Zn(NO₃)₂.6H₂O as main precursors. The physical characterization were investigated by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). As a comparison, pure SnO₂ nanofibers were also prepared. It shows that the crystals phase intensity is proportional to the annealing temperature. While the diameter size of the fibers strongly depends on ZnO contents associated with the Kirkendall effect which describes diffusional mobility along radial direction during annealing. The electrochemical performances were investigated in a H-type cell with 1cm² catalyst-coated carbon fiber paper as a working electrode. While an Ag/AgCl electrode was used as a reference electrode along with a Pt coil as a counter electrode. The aqueous solution of KHCO₃ and KOH were used as catholyte and anolyte respectively, with Nafion 115 as the separator. The quantitative analysis were caried out by gas chromatography (GC) and high-performance liquid chromatography (HPLC) to investigate the FE, PCD, and concentration of formate.