A one-dimensional model has been developed to predict NO emissions from valveless, gas-fired Schmidt-type pulse combustors. The model is based on both the Zeldovich (thermal NO) and Fenimore (prompt NO) mechanisms with the objective of studying the relationship between combustion frequency, pressure amplitude and air/fuel ratio and the formation of NO. The model incorporates a heat transfer sub-model to allow for enhancement of convective heat transfer in pulsating flows. Results of the predictions showed that lower NO formation was obtained at higher combustion frequency and higher maximum positive pressure amplitude. These trends were found to be in good agreement with experimental results. Results indicated that the volume of fresh mixture admitted per cycle in combination with the cycle time were of greater significance than bulk heat transfer rates in determining the quantity of NO formed in the combustor.