Transition metal nitrides are known to be catalytically active materials. Recently, much attention has been given to transition metal oxinitrides that may constitute a novel family of catalysts with basic or acido-basic properties. It is useful to synthesize such compounds with a high specific area. We have investigated a new family of compounds, the oxinitrides of vanadium and aluminum. Interesting catalytic activity is expected from the coexistence of nitride sites and of vanadium sites with different oxidation states between V and III. A vanadium and aluminum mixed oxide synthesized by a soft chemistry process was subjected to thermal nitridation under ammonia. Control of the vanadium/aluminum ratio is possible, which allows control over the nitrogen content in the final compound. A high specific area can be preserved during the thermal process of nitridation. When the nitridation temperature is 600 degrees C, an amorphous oxinitride of vanadium and aluminum is obtained with a specific area higher than 200 m(2)g(-1), depending on the V/Al ratio.