The polymer electrolyte membrane (PEM) electrolysis cell is a promising prospect for the production of clean hydrogen by energy of renewable wind and solar sources. One component of the PEM electrolyzer is the bipolar plate (BPP), which serves as a multifunction component during PEM water electrolysis. Titanium is typically regarded as the state-of-the-art material. Mechanically it could potentially be replace by lower-cost materials such as stainless steel, but under the harsh environmental conditions present in PEM water electrolysis, stainless steel is not corrosion-resistant and metal ions can dissolve. In this case metal ions would poison the catalyst and membrane, which leads to a reduction in the cell performance [1]. We have tested several coatings such as Au and TiN in PEM water electrolysis environments of varying severity for the application as a protective layer of bipolar plates. In order to determine possible candidates for a long-term test under real simulated PEM water electrolysis conditions, an experiment to determine pH value in PEM water electrolysis operation was developed to obtain the required pH value for the ex-situ testing of various coating materials. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.