Fly ash is an industrial by-product from combustion of coal at thermal or electric generating power plants. Fly ash is also used to improve material properties in brick or in cement. The properties of the fly ash itself depend primarily on the type of coal burned. Its chemical, physical and mineralogical properties together with its availability, make fly ash very attractive for applications in materials development. In order to further exploit the use of fly ash in materials development, it is necessary to study its microstructure with scanning electron microscopy (SEM).