The pyrolysis of agglomerating coal was analyzed by thermogravimetric analysis (TGA) coupled to microgas chromatography (mu GC) to determine the effects of reactor confinement on solid product yield, tar evolution, and gas composition. The primary volatile products generated from pyrolysis are studied using two TGA crucibles with height to width aspect ratios of 0.11:1.0 and 2.0:1.0 for heating rates of 1, 3, and 10 K min(-1). Mass balances were determined from measurements of the solid residual, gaseous flow rates, and tar products captured via glass impingers. The measurements resulted in mass balance closures greater than 99%. The higher aspect ratio confinement provided a zone where the residence time of volatile species was extended to 0.35 s from 0.04 s for the low aspect ratio confinement. The extended residence time was found to increase the solid yield by 0.6-5.7% for the low and mid ranged volatile material coals by secondary tar reactions which form coke. There was a trend of increasing solid yield with a decreasing heating rate because of the shorter residence time of the released volatile material at the higher heating rates. A decrease in tar production by 2.1-2.5% was observed in the higher aspect ratio confinement. The differences in product evolution between the two confinements were determined to be due to reactions occurring in the range of 783-848 K, which produce hydrogen, methane, and coke. hi the confinement of higher aspect ratio, hydrogen production increased by 10% and 30% for low and mid VM coals, respectively, along with a 40% increase in methane production for both coals. The higher productions of methane, hydrogen, and solid residual between 820 and 1100 K for increased residence time of 0.27-0.35 s are due to demethylation and recombination reactions during the formation of char from recondensed tar products.