Green hydrogen research progress and trends in Sub-Saharan Africa (2005–2025)

• This study systematically reviewed two decades (2005-2025) of green hydrogen research in Sub-Saharan Africa. • South Africa leads regional research, followed by Nigeria and Ghana. • Reported hydrogen production costs vary widely ($0.124-$22.63/kg) due to differences in technology, scale, and resource potential. • Techno-economic studies currently dominate green hydrogen research in Sub-Saharan Africa, • The findings underscore the importance of policy coherence, demonstration projects, and integrating socio-environmental considerations. Sub-Saharan Africa (SSA) faces a persistent energy crisis characterised by limited electricity access, heavy reliance on biomass and fossil fuels, and climate vulnerability. Green hydrogen has emerged as a sustainable option for decarbonising hard-to-abate sectors, enhancing energy security, and promoting sustainable industrialisation. This study applied the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework to synthesise peer-reviewed research on green hydrogen in SSA published between 2005 and 2025. A total of 96 articles were analysed to examine publication trends, collaboration patterns, thematic focus areas, and knowledge gaps. South Africa leads regional research output (13.3%), followed by Nigeria (7.2%) and Ghana (4.4%). Foreign collaborations, primarily with Germany (15.7%), China (7.2%), and the United Kingdom (5.4%), are crucial for capacity development. Thematic analysis revealed a focus on techno-economic assessments, resource potential mapping, and governance issues, with limited exploration of social, environmental, and circular-economy perspectives. The reported levelized costs of hydrogen range from $0.124/kg to $22.63/kg across the region, indicating wide spatial variability influenced by capital costs, technology efficiency, and renewable resource quality. The findings emphasise the importance of developing coherent policies, fostering regional collaboration, and implementing demonstration projects to bridge the research-to-practice gap. This review offers actionable insights for policymakers, investors, and researchers to foster inclusive, low-carbon growth and accelerate SSA's integration into the global green hydrogen economy.