This book is a monograph dedicated to hydrogen metallurgy technology in iron ore reduction in the world (mainly in China), aiming to accelerate the development of hydrogen metallurgy research and promote the low-carbon process in the iron and steel industry. This book mainly introduces the frontier theory and process technology of hydrogen metallurgy, focusing on the behavior and role of hydrogen in reducing iron ore. The specific contents include hydrogen production and storage technology, hydrogen direct reduction of iron oxide technology, hydrogen smelting reduction of iron oxide technology, plasma hydrogen reduction of iron oxide theory, and the behavior of hydrogen in blast furnace iron-making and sintering processes. This book provides a comprehensive and detailed description of the theories and process technologies involved in hydrogen metallurgy at the levels of fundamental theory, feasibility analysis, experimental studies, and industrial applications. This book can be usedas a reference for metallurgical engineering, iron, and steel metallurgy majors, as well as teachers and students, researchers, engineers, and enterprise staff interested in hydrogen and low-carbon metallurgy-related fields.