Rate data for the decomposition of ammonia in a glow-discharge flow system were obtained at 1.7 mm Hg and several current levels. Pure ammonia at 25°C was fed continuously to the reactor at different flow rates. The reaction products were observed using both optical spectroscopy and gas chromatography. A reaction mechanism for the rate steps which fits the data well is proposed. The principal feature of the mechanism is the use of two simultaneous reactions for NH2 combination. One leads to N2H4 and the other to NH and NH3.