Thermosynthesis refers to an at this moment still theoretical idea that organisms could be able to make use of heat as an energy source: the word ' thermosynthesis' is derived from the word 'photosynthesis'. The experimentally observed biological energy sources are light and food, and heat would represent a very different category. Thermosynthesis would not make generate much energy. It is however of interest for models for simple energy sources during the origin of life and for energy sources for extraterrestrial life. Go to www.scirus.com and search for thermosynthesis to find pertinent scientific publications on the subject.