Silicide layers on silicon can be thermally oxidized in such a way as to grow a layer of (metal-free) SiO2 without affecting the integrity of the silicide. The conditions necessary for this to occur depend on the rate of silicon (or metal) transport through the silicide, and on the rate of oxygen consumption at the silicide/oxide interface. These conditions can be defined in terms of the thermodynamics of silicon and metal oxidations. One obtains two equations for transport through the respective layers and one for the chemical reaction rate at the silicide/oxide interface. The simultaneous solution of these three equations enables one to determine (at least theoretically): (i) the maximum allowable drop in silicon activity at that interface, and (ii) under what conditions the metal in the silicide would oxidize concurrently with silicon. © 1990, The Electrochemical Society, Inc. All rights reserved.