The coal deposit of Dilbi-Moye Basin in southwestern Ethiopia, between 70 21'rn49" - 70 24' 31" N latitude and 360 50' 21" - 360 52' 54" E longitudes was studiedrnwith regard to sedimentological, geochemical, depositional environments andrnpossible causes of thermal variations of the basin, which have a total area ofrn31.94 km2.rnThe chemical analyses of the coal samples for the proximate, calorific valuernand sulfur content of the coals, different graphs are plotted versus each otherrnto depict the coalification pattern, and the possible thermal variations of thernDilbi-Moye Basin.rnFrom the analyzed coal samples result, the rank of Moye Sub-Basin coalsrnrange from sub-bituminous to high volatile A bituminous coals; whereas thernDilbi Sub-Basin coals range lignite B through high volatile B bituminous coals.rnThe majority of the coal seams in the Moye area exhibited higher ranks due tornthe proximity of volcanic extrusions.rnThere is no uniform increment of the calorific values and decreasing of the ashrncontent or vice versa in the Dilbi-Moye coals. However, in some cases, it isrnobserved that as the calorific value increases, the ash content also increasesrnand vice versa, across the basin.rnTherefore, the possible causes of the thermal variations of the coals of thernbasin might be in most cases the organic matter (genesis) of the fossil fuelrnand/or environment of deposition and partially the inclusion of inorganicrnmaterial into the coal. However, in some coal seams, the increment of therncalorific value emerges from the near-by trachytic or rhyolitic sills thatrncooked the underlying seams to have high heating values