In this Bureau of Mines report, time-resolved infrared emission spectra and corresponding pressure and temperature histories are reported for large-scale propagations of ch4-air, ch4-air-n2, and ch4-air-cf3br ignitions in a 12-ft-diam sphere. Absolute spectral radiances were obtained throughout combustion over the 1.6- to 4.8- Um range, and the radiance growth patterns for the h2o (2.5-Um) bands are presented as a function of methane stoichiometry and diluent concentration. Flame temperatures were determined from the co2-band emissions, which approximated unit emissivity shortly after ignition. Burning velocities are also given for some of the text- mixture compositions. Measured flame temperatures were in excellent to fair agreement with theoretical adiabatic values for the ch4-air and ch4-air-n2 mixtures; the best agreement was for the stoichiometric ch4-air mixture. The ch4-air-cf3br mixtures with > or = to 2 pct cf3br gave poor agreement with theory. The measured temperatures were significantly lower during the early stage of combustion; furthermore, the later stage of combustion was uninhibited and yielded unexpectedly high pressures.