Ionic conduction device

An ionic conduction device 10 of the kind including a tri-layer 11 including an electrolytic membrane 12 having a pair of opposed surfaces 13, 14, and a gas permeable electrode 15, 16 in contact with each opposed surface 13, 14, has a first gas flow path 22 for a first gas across one of the opposed surfaces 13, and second gas flow path 23 across the one of the opposed surfaces 13, and a third gas flow path for a third gas along the other of the opposed surfaces 14 of the membrane 12, characterised in that the device 10 includes a fourth flow path 36 through the device 10 for a heat exchanging fluid, the fourth flow path 36 bringing the heat exchanging fluid into heat exchange relationship with the tri-layer 11.