With the increased energy needs thermal power plants enlarge their production rates. In spite of high productivity in energy supplies, the concentration of fly ash filtered in the chimneys of these plants raises subsequently. Such a problem is also faced in Tuncbilek thermal power plant of Turkey. Due to the colouring capability of the relevant ashes, it was considered that their use in coloured transparent and opaque stoneware glazes could be possible. As well as examining their colouring effect in the glazes, thermal shock and stain resistance of the newly produced glazes were tested throughout the current study. The results suggest that fly ashes can be evaluated in the stoneware glazes for colouring purposes without changing any production parameter.