GAS EXTRACTION

An electrochemical cell used to separate gas from a gaseous mixture by reduction of said gas at the cathode (4) and regeneration of said gas at the anode (9) is characterised in that one or more substances formed during the cathodic reduction and/or the anodic regeneration is or are chemically converted, preferably by catalytic decomposition in a catalytic decomposition compartment (2), to produce further quantities of said gas, the gas formed by both the anodic regeneration in anodic compartment (3) and the chemical conversion in compartment (2) being recovered as the product. In an especially preferred embodiment a plurality of said cells are used in an apparatus for extracting oxygen from the air by using a cathode (4) comprising high surface area graphite powder which reduces oxygen to produce peroxyl ions, each cell being further provided, externally of the cathode compartment (1), with means (15) for catalytically decomposing the peroxyl ions produced, suitable catalysts being COFe2O4 or NiC020,.