Greek coals occur in a number of sedimentary basins and range in age from Eocene to Quaternary. The petrographic data indicate a wide variation in petrographic and chemical composition. The rank ranges from the transition zone peat – lignite to sub bituminous. There are no deposits of hard coal in the country. Lignite constitutes the most abundant type of coal in Greece and the most important of the Greek lignite deposits formed during the Pliocene and Pleistocene in shallow lakes and marches of closed intramontaine basins (Ptolemais, Florina, Drama in Macedonia, northern Greece and Megalopolis in Peloponnesus, southern Greece). The proved lignite reserves are currently estimated at 6750 Mt, excluding the 4300 Mm3 of Phillipi peat in Macedonia. There, 58% (about 3900 Mt) is considered to be economically recoverable. The probable and possible reserves are estimated to be of the order of 4000Mt. The kozane Ptolemais Amynteo Florina basins in Macedonia contain most (about 64%) of the nations coal resources. These lignites, which are all already being exploited, have a very low calorific value (at Ptolemais Amynteo, 1400 Kcal Kg at Megalopolis 900 Kcal Kg ) and high ash and low sulphur contents. The lignite production for 1992 was over 54 Mt. the greatest centre of lignite production are in Macedonia, at the opencast mines of Ptolemaida and Amynteo, and in Peloponnesus, at the opencast mine of Megalopolis. The vast majority (98%) of the extracted lignite is used for electricity generation and feeds power plants which have a total capacity of 4533 MW. The lignite-based power plants account for more than 72% of the total electricity generation of the country. Today, through detailed geological exploration and evaluation, efforts are being made to locate and develop other lignite deposits throughout Greece.