this invention discloses a portable catalytic combustion heater . fuel vapor and air are supplied to a catalyst which promotes the flameless combustion of the fuel , releasing heat . the fuel is supplied as a liquid , passes through a selectively permeable membrane such that fuel vapor exits the membrane and is fed to the catalyst . additional features such as porous supports and means of enhancing and diminishing the catalytic rate of combustion and controlling the heat output are also shown . this invention can be used to heat apparel , blankets , food , dwellings , containers , machinery , insect attractants , humidifiers , and perfume generators .