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During the Miocene a number of fault-bounded basins developed in Central Anatolia, Turkey. These basins were filled initially with coarse clastic material. Upward fining of the clastics during basin-fill, with an increase in the amount of clay and carbon content, led to the development of relatively shallow limnic basins in which extensive peat deposits accumulated. One such basin at Çayirhan, near Beyparazi, contains thick laterally extensive lignite seams. These lignites are characterized by their high sulphur content (up to 8.20n an air-dried basis). It is suggested that hydrothermal processes are responsible for the increased sulphur contents of the Çayirhan lignites, resulting from sulphate and sulphide precipitation. The mineral matter contains ubiquitous zeolites. The presence of heulandite in the first seam and analcime in the second seam may be a result of depth-temperature control on the distribution of zeolites in the lignite; but these differences are more probably the result of variations in the chemistry of the circulating fluid. Study of the sulphur content reveals three types of sulphur distribution, namely, vertical variation within individual seams, variation between seams and lateral variation across the basin. The first two are related to variations in the chemistry of the mineral matter in the lignite, and the last is probably related to structural/topographic control of the mire at the time of formation.