The Power Technology Division of the NASA Lewis Research Center is developing thermal control technology several applications. In the area of thermal control of power electronics heat pipes with dielectric working fluids are being developed so that electronics can be placed directly in the wick structure and submersed in the working fluid. Also, heat pipes micro machined directly in silicon are being develop. These micro heat pipes could be machined on the back of a chip to increase it's effective thermal conductivity by a factor of four. A new Multi Chip Module concept is being developed which features an all silicon assembly with an integral heat exchanger. In the area of heat pipes, Lewis has built a test facility which can, with great accuracy measure heat input and output at high temperatures and heat loads. In the area of space radiators Lewis is developing a graphite/aluminum panel which has substantially lower mass than current state of the art panels.