Abstract: There is disclosed a shoe with an internal warming mechanism that includes a heat engine and, in particular, a heat engine operating on a substantially or quasi-Carnot cycle. The warming mechanism has a compressor for compressing a gas, a condenser for condensing the gas into a liquid, an expansion and evaporator zone for expanding the liquified gas into a gas and a return line to cycle the expanded gas to the compressor. The source of energy for compression of the gas is the movement of the wearer's foot in the shoe, and the heel of the shoe has a hollow cavity in which the gas compressor is located. The sole of the shoe has an internal heel plate which is coupled, on its undersurface, to a post which is mechanically linked to the gas compressor such that up and down movements of the post in response to the movement of the wearer's heel will drive the compressor and provide the necessary work to drive the heat engine.