To apply a thermoelectric device to power generation from waste heat from an incinerator or steel factory, large size thermoelectric device or module is required. Thermal spraying is the potential candidate as a processing tool for such a device because it enables a thick layer (to 5 mm or more) to be formed with a simple and short process on large plates or long pipes, which can be inserted directly within the furnace or heat exchanger. Co-doped n-type FeSi/sub 2/ powder was prepared, and a thermoelectric device was formed by plasma spraying with 43 kW plasma under inert atmosphere. FeSi/sub 2/ layer with the thickness of 3-5 mm was formed on a stainless steel (SUS430) plate (100/spl times/100 mm) and pipe (diameter: 25 mm). The properties, microstructure and performance of thermal sprayed beta-FeSi/sub 2/ thermoelectric device was evaluated.