An experimental methodology based on thermography techniques has been developed and implemented with the aim of finding emissivity values of forest fuel flames. In this paper, previous works by different authors are discussed and theoretical fundamentals of heat transfer by radiation and of infrared thermography on which experimental method relies are briefly described. Then, designed methodology, equipments, devices and experimental tests are detailed in depth. Finally, analysis procedure is pointed out and some conclusions from the study of theresults are announced.