Systems and methods for recovery of gaseous substances from molten salt electrolysis are generally described. Certain systems comprise a cell configured for molten salt electrolysis; a collector fluidically connected to the cell and configured to collect volatilized molten salt from the cell; and a gas scrubber fluidically connected to the collector and configured to at least partially remove a gas from an effluent stream of the cell. Some methods comprise, using a pressure gradient: transporting a gas comprising molten salt vapor from an electrolytic cell to and through a collector such that at least a portion of the molten salt vapor forms a solid within the collector; and transporting some or all of the gas from the collector through a gas scrubber.

A CO.sub.2 collection system is configured to collect CO.sub.2 by bringing CO.sub.2-containing gas into contact with a reaction liquid containing NaOH and stored in a reaction tank to produce a target product. The target product to be extracted from the reaction liquid is adjusted according to a maximum temperature of the reaction liquid after production of NaHCO.sub.3 in the reaction liquid, an extraction temperature that is a temperature of the reaction liquid when the target product is extracted from the reaction tank, and an initial concentration of the NaOH in the reaction liquid.