A method of preparing substantially homogeneous aluminum oxynitride powder and other nitrogen-containing powders is provided. Particularly with respect to the AlON powder, the method comprises the steps of milling a mixture of aluminum and aluminum oxide in a nitrogen-containing atmosphere until a milled powder composed of aluminum-nitrogen solid solution and aluminum oxide forms. The next step is heating the milled powder in the presence of an inert gas and keeping it at sufficient temperature for a sufficient heating time to form the substantially homogenous aluminum oxynitride powder. This method is extended to the preparation of other powders by employing appropriate starting materials. The resultant powders are also claimed as part of the instant invention.