Coal petrological investigation along with proximate and elemental analyses were undertaken to determine the petrographic characteristics of the Apofysis lignites (Amynteo basin, Northwestern Greece) and their depositional environment. Eight samples (representing different lignite beds of the Apofysis deposit) were collected from a borehole. The Apofysis lignites have an Eu-ulminite B reflectance of Rr=0.22%, and in terms of lithotype belong to matrix soft brown coals. Huminite is the most abundant maceral group and consists mostly of humodetrinite. Inertinite has relatively low percentages whereas liptinite concentrations are low in the lower lignite beds and higher in the upper ones. Ternary plots and facies indices were employed in order to investigate the palaeoenvironment. The depositional environment of the Apofysis lignites is not definitely ascribed to a forest swamp or a reed marsh environment. The high ash content of the analysed samples is a clear indication of a topogenous setting. Low tissue preservation index (TPI) and high gelification index (GI) values are observed. High alkalinity and strongly reducing conditions may be inferred from the presence of syngenetic (framboidal) pyrite, the low TPI values which indicate high bacterial activity, and thus high pH conditions, and the preservation of gastropod shells and chlorophyllinite. High GI indicates a constant influx of calcium-rich waters into the coal swamp. The Apofysis lignite deposit may be interpreted to be autochthonous to hypoantochthonous. The peat accumulation was governed by a high groundwater level (wet telmatic to limno-telmatic facies) and a moderate subsidence rate. (C) 2003 Elsevier Science B.V. All rights reserved.