The hydrodenitrogenation (HDN) of indole has been studied over Mo2N and Mo2C with different structures. The difference in activity was modest and the structure of the catalysts exerted a more significant effect than the chemical composition. More evident difference was observed in selectivity, and here the composition was the most important factor. Sonochemically prepared Mo2C was an active catalyst for HDN reaction. It formed plate-like aggregates of loosely packed Mo2C (fcc) particles. The crystallinity of sonochemically prepared Mo2C was improved during the reaction, and its behavior in HDN became similar to Mo2C (fcc) prepared by the TPR method.