A large collection of well-characterized coals, documented in the CAER's database, was used to predict the CO2 content of maceral concentrates from Kentucky and Illinois coals. The data showed no correlation between CO2 vs. coal ranks and CO2 vs. maceral content. Subsequently, eight sets of low-ash density-gradient centrifugation maceral concentrates from five coal beds were examined, spanning in the high volatile rank range. Heating value was not determined on the concentrates, but instead calculated using the Mott-Spooner formula. There was a good correlation between predicted CO2 and maceral content for the individual iso-vitrinite reflectance (analyzed on whole parent coal) sets. In general, the predicted CO 2 increases from liptinite-rich through vitrinite-rich to inertinite-rich concentrates (note: no "concentrates" are absolutely monomaceral).