This work describes the reactivity of Schrock-type alkylidenemolybdenum(VI) complexes, Mo(=CHCPhMe2)(= NAr)((OBu)-Bu-I)(2), I, or Mo(= CHCPhMe2)(= NAr)[OCMe(CF3)(2)](2), II, with the surface of silica, silica-alumina and niobia. In situ FT-IR studies suggest that I and II are attached to the surface of silica via a Lewis acid base adduct; on silica-alumina, an OH addition to the Mo=N bond seems to take place. Grafting of I and II causes a decrease in their intrinsic catalytic activity as well as a change in the stereoselectivity of II in ROMP of norbornene.