Knowledge of the spectral emittance of coal particles is necessary for the measurement of particle temperature, devolatilisation rate, rate of particle heat up, and power radiated by the particle during combustion and gasification. Information on the development of emittance of coal particles which are devolatilised and burnt, as well as information on the emittance of char as a function of ash content are rare. This article examines the evolution of spectral emittance of coal particles as these are devolatilised Two different coal samples were used in this study. Spectral emission measurements were carried out on opaque layers of coal particles at wavelengths between 2 and 12 mu m, and progressively at temperatures from 200 degrees C to 1000 degrees C to illustrate the effects of particle size and coal type on emittance, and more importantly the development of emittance with devolatilisation. From one coal, char samples were generated in a drop tube furnace at three different burnout levels. Spectral emission measurements were carried out on opaque layers of these char particles to illustrate the effects of burnout and ash levels on emittance. Such measurements covering a wide range of temperature and wavelength are one of the very few reported in literature. The implications of these results on pyrometry are briefly discussed to illustrate the magnitude of potential errors in temperature measurement.