Organosilicon compounds having organyloxy groups are prepared by reacting an organosilicon compound (A) having at least one silanol group with a compound (B) containing at least two organyloxy groups in the presence of a component (C) comprising a zinc chelate (C1) and at least one additive (C2) selected from the group consisting of compounds containing basic nitrogen (C21) and alcohols (C22). The products are useful in compositions which crosslink at room temperature.