Degradation of ferroelectricity in PZT (Pb(Zr0. 52, Ti0. 48)O3) thin-film capacitors caused by heat treatment in a reductive ambience is investigated. We have found that the degradation of ferroelectricity depends upon the metal used for the top electrode of the PZT capacitor. The increased degradation in the case of a PZT capacitor with Pt electrodes can be explained by a catalytic reaction on the Pt surface. With the use of an IrO2 non-catalytic top electrode, we have made the ferroelectricity of an IrO2/PZT/Pt capacitor retained even after the H2 annealing at 400, or above.