A laboratory scale gasifier has been used to investigate the reaction conditions allowing the formation of high concentrations of NH3 in a pilot scale, air blown gasifier. Ammonia has been shown to be produced during the pyrolysis of the coal volatiles and by a reaction between steam (or H-2 produced by its decomposition) on the N present in the char after pyrolysis. The latter reaction produced the higher proportion of the total NH3. The effect of the gasifier operating conditions on the amount of NH3 formed by the reactions has been studied, which has led to the identification of ways to minimize the amount formed. The main control options to consider are using an alternative method of bed temperature control (i.e., avoid the use of steam), operating with higher bed temperatures (with the limit set by ash melting), and operation at lower pressures (within limits set by power generation efficiency considerations).