In the context of the global climate crisis, the development of efficient carbon capture materials is gaining urgency. Anthropogenic CO 2 emissions are the main contributor to increasing atmospheric greenhouse gas concentrations, directly resulting in threatening global temperature rises. In order to limit global warming to 1.5 • C both vast emissions reductions and negative emission technologies are now required. Carbon capture and storage is positioned to play a central roll in both transitioning to zero-carbon energy sources and as a direct carbon dioxide removal technology to counterbalance residual greenhouse gas emissions. The development of new materials, particularly for direct air capture (DAC), is one of the key areas of research required for achieving economical technological scale-up. Traditional amine-based sorbents, used in point-source capture, suffer from both oxidative degradation and low efficiency regeneration in solvent based systems. Hydroxide-based solid sorbents, however, are an emerging class of alternative materials, particularly for DAC. The solid-state hydroxide chemistries are more robust to oxidative degradation and avoid the corrosion problems associated with solvent-based amine capture. A growing body of work is focusing on hydroxide-based materials for DAC, however, detailed mechanistic information can often be challenging to obtain, hindering further materials optimisation and development.