High-temperature industrial processes (>1000 °C) represent a critical frontier for decarbonisation. This chapter assesses the role of clean hydrogen as a fuel for these hard-to-abate sectors, including refining, glass, ceramics, and non-ferrous metals. The analysis positions hydrogen not as a universal solution, but as a targeted option for specific applications where its flame-based characteristics are advantageous or where electrification faces technical barriers. It details the technical challenges of burner retrofits, combustion dynamics, and materials compatibility, and provides a comparative analysis with competing electrification technologies. The chapter concludes that while hydrogen holds promise, its adoption will most likely be niche and cluster-dependent, requiring significant policy support and co-evolving with a broader portfolio of decarbonisation solutions.