The objective of the study was to characterize changes of reflectance, reflectance anisotropy and reflectance indicating surface (RIS) shape of vitrinite, sporinite and semifusinite subjected to thermal treatment under inert conditions. Examination was performed on vitrinite, liptinite and inertinite concentrates prepared from channel samples of steam coal (R-r=0.70%) and coking coal (R-r= 1.25%), collected from seam 405 of the Upper Silesian Coal Basin. The concentrates were heated at temperatures of 4001200 degrees C for 1 h time in an argon atmosphere. All components examined in this study: vitrinite, sporinite and semifusinite as well as matrix of vitrinite and liptinite cokes, despite of rank of their parent coal, show, in general, the most important changes of reflectance value and optical anisotropy when heated at 500 degrees C, 800 degrees C (with the exception of bireflectance value of sporinite) and 1200 degrees C. After heating the steam coal at 1200 degrees C, the vitrinite and the semifusinite reveal similar reflectances, whereas the latter a slightly stronger anisotropy. Sporinite and matrix of liptinite coke have lower reflectances but anisotropy (R-bi and R-am values) similar to those observed for vitrinite and semifusinite. However, at 1000 degrees C sporinite and matrix of liptinite coke have the highest reflectivity of the studied components. The RIS at 1200 degrees C is the same for all components. The optical properties of the three macerals in the coking coal become similar after heating at 1000 degrees C. Coke obtained at 1200 degrees C did not contain distinguishable vitrinite grains. At 1200 degrees C semifusinite and vitrinite coke matrix have highest R, values among the examined components. Maximum reflectance (R-max) reach similar values for vitrinite and sporinite, slightly lower for semifusinite. Matrix of liptinite coke and matrix of vitrinite coke have considerably stronger anisotropy (R-bi and R-am values) than other components. RIS at 1200 degrees C is also similar for all components. (C) 2006 Elsevier B.V. All rights reserved.