The paper provides a summary of safety characteristics of hydrogen and hydrogen fuel gases. The investigations focus on water electrolysis, the feeding of hydrogen into the natural gas grid and the use of hydrogen for the fermentation process in biogas plants. The safety characteristics of hydrogen such as very low minimum ignition energy, very large explosion range and high flame velocity with the resulting rapid pressure increase of hydrogen explosions are of particular importance for explosion protection and they differ strongly from those of natural gas. Explosion ranges of hydrogen-methane-carbon dioxide mixtures have been measured for the use of hydrogen in biomethane production. The paper also shows and discusses explosion ranges of hydrogen and hydrogen-natural gas mixtures. Pressure and temperature dependencies of the explosion limits of mixtures were investigated. Furthermore, pressure rise rates (K-G values) were measured with regard to constructive explosion protection. The maximum experimental safe gaps were determined for the classification of the mixtures and assignment to explosion groups according to the European ATEX directives. It was found that admixture of 10% hydrogen to natural gas has only a minor influence on the safety characteristics of gas explosions. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.