Experiments covering a broad range of reaction conditions are being conducted to determine and model the effects of coal gasification environments on product yields. The research uses a 3-in ID, downflow entrained reactor that turbulently mixes preheated gases with coal to achieve high particle heating rates. As part of a comprehensive experimental program, pyrolysis tests reacting Montana Rosebud subbituminous coal in a nitrogen-argon atmosphere were completed to provide baseline yield data for eventual comparison with tests in reactive environments. The tests consisted of a three-variable, composite factorially designed series, a single test at extreme reaction conditions, and a limited series to investigate particle size effects. Experimental conditions ranged from 1500/sup 0/ to 2500/sup 0/F reaction temperature, 100 to 900 psig pressure, 2.19 to 10.00 s gas residence time, with gas preheat temperatures up to 3000/sup 0/F. This report provides the basis and background of this work; describes experimental equipment, procedures, and design; presents test data and regression model analyses; and discusses statistically significant trends in relation to the current understanding of devolatilization and secondary reaction phenomena. 29 refs., 98 figs., 75 tabs.