Power-to-Gas is a promising way to achieve climate goals by reducing CO2 emissions, store larger amounts of renewable electrical energy from wind and sun through the production of hydrogen by electrolysis, and then possibly inject it into the natural gas grid. As a consequence, end users of natural gas across all sectors could be confronted with higher and fluctuating concentrations of H2 in the locally available natural gas and there are concerns, particularly in the thermal processing industries, how these changes in the fuel composition might impact product quality, efficiency and NOX emissions of gas-fired manufacturing processes. Within the framework of an AiF research project, the Gas- und Wärme-Institut Essen e. V. (GWI) has investigated these issues by analyzing the impact of high and fluctuating hydrogen contents (up to 50 vol.-%) on various industrial burner systems, using both simulation and experimental methods. The effects on operational aspects such as combustion behaviour, flame monitoring and pollutant emissions were analysed. Based on this, solution concepts and compensation strategies for thermal process industry were developed and presented. © 2020 Vulkan-Verlag GmbH. All rights reserved.