In this work an electroacoustic technique was used to characterize the dispersing behavior of alumina in water with or without the addition of an anionic polyelectrolyte as dispersant. Electroacoustic measurements enabled the zeta potential and particle size distribution to be noted; additionally, the in situ measure of the conductivity allows the ionic strength to be simultaneously determined. In this way the pH or dispersant contribution to powder stabilization has been evaluated. With this technique important colloidal parameters such as the isoelectric point and particle size distribution at various solution or powder conditions (alumina vol%, pH, dispersant wt%, milling time) can be measured and the minimum amount of dispersant (Duramax D3021) required to cover completely the powder can be easily estimated. Copyright 1999 Academic Press.