A flat plate heat exchanger and heat exchange plate members for use therein, the heat exchanger having a support structure which includes one or more elongate support members; the plate members each having a generally flat plate portion formed of a heat conductive material, a recess formed in an edge portion thereof for accommodating an elongate support member, and a flexible arm formed in association with the recess and arranged for flexing in a direction which is in the plane of the plate member for snap coupling and decoupling with the elongate support member, such that the plate member is supported thereby.