The concentration of atomic sodium in the plume of single brown-coal particles burning in a flat flame environment is measured using quantitative planar laser-induced fluorescence (LIF). A run-of-mine Loy Yang brown coal (LY-ROM) and two Loy Yang brown coals (MTE1 and MTE2) that were processed using Mechanical/Thermal Expression, which removed a fraction of the inherent moisture and concomitant dissolved salts, were investigated. By applying a chemical equilibrium model, at an appropriate location in the flame, the total sodium release is estimated from the measured atomic sodium concentration profile. For LY-ROM, MTE1 and MTE2 the total proportion of sodium release following devolatilisation, as a percentage of the initial sodium in the coals, was 80.9 +/- 19.5%, 87.9 +/- 19.0% and 93.0 +/- 28.0% respectively. Using this data, it is inferred that approximately 67% of water-bound sodium and approximately 100% of the organically-bound sodium is released following devolatilisation. Furthermore, in the present experiments up to 60% of the total sodium is released during the period in which the ash remains within the flat flame, following char combustion. A mechanism is proposed to explain this observation in which Na2O in the ash reacts with ambient water vapour at high temperature. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.