This chapter provides an in-depth examination of hydrogen as a clean and sustainable energy source for heat supply, focusing on its potential to decarbonize various heating applications. It covers hydrogen production technologies, including electrolysis and steam-methane reformation, with particular emphasis on green hydrogen produced from renewable sources. The book also explores different hydrogen storage methods, including liquid hydrogen and compressed hydrogen in cylinders, essential for ensuring efficient supply and usage. The role of hydrogen in fuel cell technology analysed, highlighting its potential for high efficiency and low emissions in heating systems. A chapter devoted to practical considerations for integrating hydrogen into heat supply, including necessary equipment, system maintenance, and performance assessment methodologies. Real-world case studies presented to illustrate how hydrogen used in district heating networks and industrial heat supply systems. The chapter also offers a comparative analysis of different hydrogen production scenarios—baseline, maximum capacity, smoothing, and decarbonization—providing insights into the economic feasibility and environmental benefits of hydrogen in heat supply. The decarbonization scenarios, with and without infrastructure modifications, thoroughly examined to determine how hydrogen contribute to reducing carbon emissions in the heating sector. This chapter emphasizes the critical role of hydrogen in the global transition to a low-carbon energy system, highlighting its ability to provide sustainable heat supply solutions for industries and cities alike. Through detailed technical analysis and case studies, the book provides a roadmap for implementing hydrogen-based heat supply systems to meet future energy demands and climate targets.