High-purity hydrogen generation for primary energy production is one of the main goals of the renewable energy consumption model. In this regard, water electrolyzers (WE) are projected to fulfil this requirement since they can be coupled to renewable sources, which provide the necessary energy to generate the water splitting reaction. Nowadays, no-noble materials are usually employed as low-cost catalysts to overcome the hydrogen evolution reaction (HER). However, kinetics and mechanistic studies of the HER from faradaic currents is becoming more challenging due to the overlap of by-side reactions such as catalyst oxides reduction. Herein, for the first time ionic currents from differential electrochemical mass spectrometry (DEMS) are employed to overcome this issue. Thus, the m/z = 2 signal is followed during the hydrogen evolution on tungsten-based catalysts in basic medium and accurate Tafel slopes are achieved and the rate determining step (RDS), as well as the reaction mechanism can be easily attained. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.