Abstract: A portable heater for generating and circulating heat in wearing apparel and consisting of a closed container for containing a liquid heat transfer medium therein and a second container which is received in the closed container and is adapted to receive a heat evolving means therein such as a combustible fuel stick of the type utilized in conventional hand warmers, the heat evolving means being received through an opening to the exterior of the improved heater assembly. A portion of the exterior walls of the second container are exposed in heat exchange relationship to the interior of the closed container for efficient heat transfer through the walls of the second container to a liquid heat transfer medium contained within the closed container.