This study is an attempt to find useful relationships between the petrographic characteristics of coals and their efficiencies during pulverized fuel combustion through the study of their pyrolysis chars, Specifically, the effects of coal rank have been investigated using a series of vitrinite-rich coals ranging from subbituminous to low volatile bituminous coal. The behavior of these coals during combustion at 500 and 1100 degrees C and the petrographic characteristics of their pyrolysis chars (1000 degrees C) were investigated. In a foregoing paper (Borrego et al.(10)), unexpectedly poor combustion performances were found for some hvBb coals, which were attributed to rank rather than maceral effect. A general pattern of variation of coal burnout with rank was found in this study, providing additional data in which those unexpected results could be fitted. The observed trend was explained in terms of the changes undergone by coal both during coalification and pyrolysis, which make the number and accessibility of active sites vary in opposite directions, thus leading to a nonuniform variation of coal combustion efficiency with rank.