Within the framework of modified Landau-Devonshire thermodynamic theory, the equilibrium polarization states and physical properties of single-domain Pb(Zr1-xTix)O-3 (PZT) thin films epitaxially grown on dissimilar cubic substrates are investigated. The "misfit strain-temperature" phase diagrams are obtained for several different compositions (x=0.75, 0.65 and 0.55) of PZT films. The presence of stability range of the monoclinic phase is the characteristic feature of these phase diagrams, which separates the stability ranges of the tetragonal phase and the orthorhombic phase. Further analysis shows that the monoclinic phase widens with the increase of Zr content, and meanwhile the center shifts from positive values of the misfit strain towards zero. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.