Electrochemical impedance spectroscopy is used to monitor the real-time network response of 1 cm(2) areas of ferroelectric PbZr0.52Ti0.48O3 (PZT) thin films solution deposited onto platinized silicon wafers and exposed to 0.1 N H2SO4 over 48 hours. Development of equivalent circuits to model the competing processes of pore growth, interfacial layer formation, and uniform chemical attack are guided by the evolution of film structure and chemistry as observed ex-situ in SEM, X-ray photoelectron spectroscopy, and X-ray diffraction. In areas containing cracks or pores, corrosion is accelerated. After prolonged exposure, growth of an amorphous film of PbSO4, sulfate-doped zirconia, and lead-deficient PZT proceeds into the PZT film, with PbSO4 crystals nucleating atop this interfacial layer. The Point Defect Model for the passive state is used to explain the dissolution processes observed in the complex oxide. Application of this model to PbZrxTi1-xO3 for x = 0.25, 0.52, and 0.95 points to the role of titanium in the creation of an ionically insulating layer that impedes further chemical attack. (C) 2013 The Electrochemical Society. [DOT: 10.1149/2.005304jes] All rights reserved.