This book aims to explore the role of hydrogen as a promising alternative to fossil fuels, particularly in the transport and heavy-duty sectors. As global efforts to reduce greenhouse gas (GHG) emissions accelerate, policymakers are increasingly focusing on hydrogen to achieve net-zero targets. While battery electric vehicles (BEVs) are expected to dominate the market for two-wheelers (2Ws), three-wheelers (3Ws), and personal cars, hydrogen-fueled internal combustion engines (ICEs) are emerging as a key solution for buses, heavy-duty trucks, construction machinery, agricultural equipment, and non-road applications. This book presents an in-depth analysis of hydrogen-fueled engine technology, discussing its advantages, challenges, and future potential. It highlights how hydrogen-fueled engines eliminate emissions of particulate matter, carbon monoxide (CO), carbon dioxide (CO2), and volatile organic compounds (VOCs). However, nitrogen oxides (NO?) emissions remain a challenge, which can be mitigated through advanced after-treatment systems and optimized engine operating conditions. This book focuses on various hydrogen production technologies, recent advancements in hydrogen-fueled internal combustion engines, and novel fuel injection strategies for achieving efficient and knock-free hydrogen combustion. It covers a wide range of topics, including port fuel hydrogen injection, diesel pilot ignition, hydrogen production from alternative sources, and the challenges of hydrogen storage and distribution. Additionally, it examines the role of hydrogen in maritime applications and its potential as a future fuel for internal combustion engines. Through a comprehensive discussion of cutting-edge research and technological innovations, this book provides valuable insights for researchers, engineers, policymakers, and industry professionals working toward a sustainable hydrogen-powered future.