A novel and simple synthesis methodology based on ion adsorption process is reported for K0.4TaO2.4F0.6 nanocubes supported on carbon (K0.4TaO2.4F0.6 NCs/C), and used as electrocatalyst for hydrogen evolution reaction (HER) in the acidic media. The K0.4TaO2.4F0.6 NCs/C exhibits outstanding catalytic activities and stabilities for HER. The X-ray absorption fine structure (XAFS) analysis indicates stronger binding energy and electron transfer from metal element to fluorine, which leads to higher HER performance, proved by the density functional theory (DFT) calculations. (C) 2017 Elsevier Ltd. All rights reserved.