In the context of planning a decarburization of the European Union energy sector, in order to reach a reduction of carbon emissions up to 95% by 2050, several studies on the compatibility of the existing gas networks with blends of natural gas/hydrogen up to 20% of hydrogen have been tested in industrial scale projects. In relationship to the European Union ATEX directive 2014/34/EU covering equipment and protective systems intended for the use in potentially explosive atmospheres, gases and dusts are classified according to their ignition properties. The explosion group for gases and vapors is determined by the maximum experimental safe gap (MESG) and/or minimum ignition current (MIC) ratio values, both defined in the IEC 60079-20-1 (Explosive Atmosphere-Part 20-1: Material characteristics for gas and vapour classification Test methods and data) standard. This paper reports the results of the experimental determination of MIC of methane/hydrogen mixtures up to 20 vol.% of hydrogen. We present the ratios of MIC for hydrogen/methane blends to the MIC of pure methane as well, in order to classify these mixtures into gases groups. The interpretation of our results would lead us to conclude that methane/hydrogen mixtures containing 16 vol.% of hydrogen or more should be Group IIB gases. However, other results available in scientific literature and standards lead to the conclusion that these concentrations would still remain within the Group IIA classification. This issue was recently discussed in the IEC subcommittee 31 M of the International Electrotechnical Commission, in order to resolve this contradiction. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.