The impact of different additives on the hydrolysis of AlN powder in aqueous suspensions at room temperature was studied. The results show that citric acid and polyacrylic acid are most effective in chemically protecting AlN against hydrolysis. The protected powder is hydrophilic, which facilitates aqueous processing, and the chemical stability is retained when basic dispersing agents are added. Based on these results, the solid loading of the aqueous slurries was maximized by utilizing bimodal particle size distributions. Combining bimodal powders with the dispersants Dolapix and citric acid, colloidally stable slurries with solid loadings in excess of 50 vol% were obtained.