Clean hydrogen is widely projected to be a cornerstone of the global energy transition, particularly for decarbonising hard-to-abate sectors. This chapter provides a comprehensive analysis of the key hydrogen production technologies—covering conventional, low-carbon, and emerging pathways—and their associated costs. It traces the historical evolution of hydrogen production and employs a transparent Levelised Cost of Hydrogen (LCOH) methodology to critically assess current and projected costs. The analysis reveals a significant gap between the optimistic cost assumptions in international roadmaps and the current realities of project economics, driven by challenges in technology scalability, infrastructure rollout, and supply chain constraints. The chapter concludes that while hydrogen’s potential is substantial, its future role will be forged by pragmatism, requiring targeted deployment in specific sectors and regions rather than a one-size-fits-all approach.