The Amasra coalfield is a part of the Upper Carboniferous Zonguldak coal basin of Turkey within the Istanbul zone, a Hercynian deformed unit forming the eastern continuation of the Moesian platform in SE Europe which was later deformed by Alpine tectogenesis. The mainly Westphalian aged coals were sampled from an underground mine and from cores from nine exploration wells and petrographic (maceral and microlithotype) analysis and mean maximum vitrinite (telocollinite) reflectance (% R-max in oil) were determined. The coals were characterised by low ash and low total sulphur contents, abundant vitrinite-group macerals and relatively abundant vitrite, clarite and duroclarite microlithotypes. Vitrinite reflectance was in the range 0.58-1.04% R-max, indicating ranks from high volatile C bituminous to high volatile A bituminous coal. The % R-max generally increases with increasing depth in the exploration wells, with gradients ranging from 0.21 to 0.40% R-max/km and an average of 0.30% R-max/km. The highest value occurs in the south of the coalfield in a region of Hercynian folding and thrusting. The relationship between vitrinite reflectance and thrusts in the wells suggests that coal rank was developed mainly pre-thrusting but that some wells, arguably, show evidence for post-thrust coalification. Peak coalification probably occurred during Late Mesozoic-Early Tertiary rifting, so that the thrusts which developed after coalification are likely to be Alpine in age whereas the thrusts that pre-date coalification may have been Hercynian structures. (C) 1998 Elsevier Science B.V.