The air pollution characteristics of a model gas turbine type combustor using methane as fuel were studied in this investigation. Detailed information regarding gas compositions at various locations within the combustor and direct measurement of temperature within the combustor were obtained. The essential differences between air pollution characteristics of gaseous and liquid fuels used in the combustor were investigated. Performances of two nozzles employing two different gas injection velocities were compared. Influence of overall equivalence ratio on hydrocarbons and CO emissions was evaluated. Information regarding air flow distribution in the combustor was obtained. An estimate of the characteristic time of combustor flow processes was obtained. (Modified author abstract)