Pt nanofibers have been prepared with a redox reaction occurring spacio-selectively at the liquid-liquid interface between a highly hydrophobic ionic liquid (IL) and water (W), which has been utilized as two dimensional reaction field. The preparation is conducted based on the concept of the coupling between ion transfer (IT) and electron transfer (ET) across the ILjW interface, which previously enabled direct formation of dendritic Au nanofibers at the ILjW interface (Chem. Commun., 2015, 51, 13638). The successful preparation of Pt nanofibers has manifested the generality of the ILjW interface method for the formation of metal nanofibers. Electrochemical measurements at the ILjW interface have confirmed that IT of PtCl42- from W to IL is actually coupled with ET between PtCl42- initially dissolved in W and deca-methylferrocene in IL, leading to the spontaneous formation of Pt nanofibers at the ILjW interface. Herein, IT of PtCl42- ions from W to IL not merely neutralizes the excess charges generated in each liquid phase by ET, but also provides PtCl42- into IL as reactants for the growth of Pt nanofibers that takes place at the IL side of the ILjW interface. The electrocatalytic activity of the Pt nanofibers in oxygen reduction reaction (ORR) has also been evaluated. (C) 2018 Elsevier Ltd. All rights reserved.