Greece relies heavily on lignites to satisfy its domestic needs for power generation and produces some of the cheapest and most cost effective KWh within the European Community. Currently, it mines 70 tons/year of soft brown coal to cover over 70% of the country's domestic power needs. Brown coal in Greece is found in 68 coal basins of various sizes. Generally, it is of poor quality that is of low calorific values and relatively high ash content. Henceforth, a detailed knowledge of maceral and ash composition is essential to appropriately construct boilers to avoid abrasion of mechanical parts, fouling and corrosion of boilers, and to take appropriate environmental measures. Though the % composition of the maceral groups is relatively the same in almost all Greek coal basins, the % composition of maceral subgroups, especially that of huminite, varies substantially. This variation affects boiler's performance since the maximum heat release takes place at various heights inside the boiler. Humotelinitic brown coals rich in resinite release their thermal energy at lower temperatures than humocollinitic coals, which have low resinite contents. Furthermore, coal ash rich in gypsum, anhydrite and other minerals with hardness less than 3 do not affect the mechanical parts of the boiler whereas coal ash rich in quartz, feldspars and pyrites do. Finally, Greek brown coals have variable trace elemental composition. Coals from basins surrounded by carbonate rocks (Western Greece) do not exhibit high concentrations of heavy elements, whereas coals from basins surrounded by mafic rocks (North-Central Greece) are rich in Cr, Ni, Cu and Zn, while coal basins surrounded by igneous rocks (North-Eastern Greece) are rich in Ph, Zn, Co, Hg, As and U. (C) 2004 Published by Elsevier B.V.