Metal-organic frameworks (MOFs) are a well developed and studied class of material for carbon capture applications; in particular, hydroxide-based MOFs have been demonstrated to achieve high capacities and high stabilities. In most cases a metal-bound hydroxide will react with CO 2 to from a chemisorbed metal-bicarbonate species (equation 1). However, in systems with unreacted adjacent and/or labile hydroxide anions, successive capture (eq. 2) and deprotonation (eq. 3) steps may occur to from free bicarbonate/carbonate chemisorbed species. The interplay of bicarbonate and carbonate species in hydroxide capture is well discussed in the context of humidityswing sorbents. Most notably -for all hydroxide-based sorbents -there is the fundamental stoichiometric difference between bicarbonate (eq. 2) and carbonate (eq. 3) mechanisms, with a bicarbonate product mechanism capturing twice the number of CO 2 molecules per hydroxide molecule, compared to a carbonate product process. In addition, carbonate mechanisms would likely be subject to slower kinetics due to the multi-step reaction and the requirement for water dissociation for regeneration.