Bed material agglomeration and loss of fluidization present a major problem in fluidized bed combustion or gasification of low rank coals. Ash particles start to agglomerate and fluidization becomes unstable at temperatures well below the ash softening point measured by the ASTM methods. Attempts have been made to develop a method to determine this characteristic temperature. This paper presents results from an investigation into thermo-mechanical analysis (TMA) as a potential technique. It is shown that, when applied to the coating materials at a heating rate of less than 5 degrees C/min under a force of 0.5 N, the technique can successfully detect the point at which the particles change its spouting or fluidization characteristics.