Residues obtained by supercritical water extraction of coals of various coalification degrees and lithotypes of low rank coal were examined under the microscope. The optical texture of residues is closely connected with the rank of the original coals and their petrographic composition. Supercritical conditions of coal extraction with water appear to have a favourable influence on the formation of porous structures and the development of optical anisotropy in residues. The optical texture of the examined residues is similar to the texture of metallurgical cokes.