The Achlada and Mavropigi lignite deposits in northern Greece provide the main coal source for the next generation of Greek power plants. A comparative characterization of these two lignite deposits is presented, covering the coal rank and the features of the maceral components, based on detailed coal petrography, and the mineralogical and geochemical features of the coals and their ashes, based on XRF and XRD analyses. The data are used to interpret the palaeoenvironments of the lignite beds, as well as factors that may affect their burnout behavior. Both deposits have a lignite C rank. The Mavropigi lignite is mainly a matrix lignite lithotype, whereas the Achlada deposit consists both of matrix and xylite-rich lithotypes. The Achlada lignite was formed in a fluviatile environment, mainly in the abandoned channels of a meandering river system during flooding periods; hence it is enriched in inorganic matter, with ash values >30 wt.%. The Mavropigi lignite formed in a reed-marsh environment under limno-telmatic conditions, and displays ash values <30 wt.%. The inorganic matter of the two deposits is different in composition due to the contrasting environments, and these differences should be taken into account in optimizing their utilization for power production. A preliminary assessment indicates that the Achlada lignite may have more favorable slagging and fouling properties than the Mavropigi lignite, although experimental studies are required for more solid conclusions to be reached. (C) 2010 Elsevier B.V. All rights reserved.