The cell (2) circulates a ternary material system consisting of a vapour/carrier mixture and a vapour absorbing solution. The cell (1) has a divided two section cell casing (2) electrically isolated by a seal (3) and contains a flat, porous and gas permeable first electrode (4) and a flat, porous, gas- and liquid-permeable second electrode (5) between which is an ion permeable membrane electrolyte (6) which together form a stable mechanical combination. The first case section (2.1) and the first electrode surface (4.2) form a channel (7) for a vapour saturated ion generating gas carrier (G,D) and the second electrode surface (5.2) and the second case section (2.2) a channel for the vapour absorbing solution (L). Connections (9,10) connect the electrodes to a resistance (11).     Vapour saturated carrier gas (G,D)r with a high vapour partial pressure enters the first case section through openings (12.1,12.2) and a reduced quantities (G,D)m with reduced vapour partial pressures are derived. An under saturated solution (L)a enters the second case section with a lower vapour concentration and vapour partial pressure through openings (13.1,13.2) and a two phase mixture (L)r , [G,D]aof under saturated solution with increased vapour concentration and lower partial pressure as well as vapour saturated carrier gas with the same low partial pressure are derived.    By using a cation generating gas and a membrane electrolyte selectively permeable to these cations anodic oxidation, with the dissipation of carrier gas and vapour from the gas channel, at the phase boundary (4.1) (gas/solid/electrolyte) causes cations to form at the first electrode. The cations migrate through the membrane electrolyte and at their phase boundary (5.2) (gas/liquid/solid) through cathodic reduction, with the release of an equivalent quantity of carrier gas, the ilquid in the liquid channel becomes more concentrated and the electrons on the first electrode flow to the second electrode via the resistance.    Using an anion generating gas and appropriate membrane electrolyte anion oxidation reverses the proces to produce a flow of electrons to the first electrode.    USE/ADVANTAGE -   For converting waste heat into electrical energy. Achieves higher energy outputs and efficiency than galvano-reaction cells and provides a stable, controllable, isobaric material circulation.