Various Al2O3-Cr nanocomposite powders were obtained by high energy milling. Measurements have been made of particle size distribution, zeta potential and acid-base properties on samples which differ by milling conditions or composition. The influence of each factor is assessed. Titration studies show that the composite product has to be handled around neutrality when dispersed in water (slight ionic strength, pH about 5.5-6) because of possible chemical reactions, particularly chromium dissolution which can occur in acidic or basic solutions. Under these conditions, composite powders behave Like the pure oxide and could be processed in similar ways.