Measurements of nitric oxide (NO) emissions were obtained from a non-premixed, methane-fired Schmidt tube pulse combustor in which combustion frequency and pressure amplitude could be varied independently. Results for a range of input firing rates, air-fuel ratios, pressure amplitudes and combustion frequencies are presented and discussed. For example, by increasing the combustion frequency from 30 to 59 Hz (at 25 kW input firing rate, stoichiometric air-fuel ratio and 0.12 bar pressure amplitude), the NO emissions reduced monotonically from 61 ppm to 29 ppm (dry ppm, corrected to 3% O-2). The general conclusion from this study was that the lowest NO emissions occurred under conditions of high combustion frequency and high maximum pressure amplitude. Possible mechanisms for this are discussed.