The disposition of the heteroatomic structures contain coal during gasification. The understanding of the behavior of the sulfur containing entities is of special importance because of environmental concerns. This investigation deals with the correlation between the structural incorporation of sulfur and oxygen and the production of hydrogen sulfide, sulfur dioxide, carbonyl sulfide, carbon disulfide as sulfur containing gases and carbon dioxide, carbon monoxide, and methane as nonsulfur containing gases. Well characterized sulfur structures were introduced into bituminous coal in low concentration by 0-alkylation methodology into the coal structure so their behavior at elevated temperatures could be monitored. Pyrolysis experiments were performed using a wire screen reactor and temperature programmed pyrolysis high-resolution mass spectroscopic techniques. The relationships between the structural components and the evolution of gases is discussed. Finally, the structural mobility of the anchoring group during the pyrolysis has been demonstrated. For example, the 2-butylthiophene fragment incorporated in coal structure was converted into benzothiophene along with many intermediate compounds. In addition, a few oxygen and nitrogen containing fragments were also introduced in coal structure and the coals were subsequently pyrolyzed. However, their behavior during the pyrolysis was not extensively studied. 83 refs., 68 figs., 26 tabs.