Abstract: Thermoelectric apparatus comprising a thermoelectric generator (101), a thermally conductive heat spreader (105) and a thermally conductive heat transfer element (103). In use, the TEG is disposed on a surface of a heated object (10), e.g. a boiler, pipe or electrical equipment. Heat is drawn away from the cold side of the TEG by the thermally conductive heat transfer element. Thermal insulation (107, 109) may be provided between the TEG and the thermally conductive heat spreader and/or over the heat spreader. The apparatus may be provided in kit form for assembly on a surface which is heated when in use.