The wettability of aluminium nitride by Sn-Al melts was studied by the sessile drop method in a vaccum of 2 x 10(-3) Pa at 1100 degrees C over the whole concentration region. The minimum interval on the contact-angle concentration dependence cu rye was observed at intermediate composition. For comparison, experiments were also performed on porous AIN. Wetting of porous nitride is worse than the dense nitride. The results have been analysed on the basis of the relation between wettability and the chemical interface reactivity in solid-liquid metal systems.