Diffuse reflectance infrared spectroscopy (DRIFTS) has been used to compare the surface structure and stability of fresh and reduced Pt-AlPON catalysts with that of AlPON support. DRIFTS reveals that surface PNH2 species participate in the anchoring process of the platinum precursor; meanwhile, the metal-phase reduction process produces a deep decrease in the specific surface and total nitrogen content of the solid. On the other hand, the three solids undergo hydrolysis in the presence of gaseous water at concentration as low as 3 ppm. As a result of this hydrolysis reaction, part of the nitride ions are transformed into easily removable PNH4+ and NH surface species.