The present paper investigates the rate of chemical dissolution of Al2O3 particles in synthetic Al2O3-CaO-FeOx-SiO2 slags as a function of time under an atmosphere where Fe2+ would be the stable state for iron ions dissolved in the slag. Two aspects of the interaction between the Al2O3 spheres and slags were studied, namely (i) the speed at which the particle sinks into the slag and (ii) how rapidly the particles dissolve. The objectives are to elucidate interactions between oxide particulate material, either from the refractory wall or from the mineral constituents in the fuel feedstock, with the slag formed at the wall in entrained-slagging gasifiers. The particle settling was found to proceed first rapidly, but subsequently slowing down and this behavior was in qualitative agreement with model predictions based on a balance between gravity-, drag-, capillary-, and added mass forces. The effect of increasing temperature and FeOx content are investigated and it is shown that both contribute towards increasing the dissolution rate. The rate appears to be governed by a combination of the driving force for dissolution and transport properties in the slag. (C) 2008 Elsevier Ltd. All rights reserved.