hi this paper, we present direct observations of local domain switching in the individual grains of 300 ran thick sol-gel PbTiO3 thin films using a piezo-response SPM. It is revealed that almost no domain switching occurs in the c-dontain region at 4 V, and partially switching takes place at 6 V. The switched domain expends the whole grain rapidly by further increasing the bias. The a-domain cannot be reoriented even at the bias up to 10 V. High tetragonality of PbTiO3 is believed to induce great strain to suppress the reorientation of a-domains. polarization contrast difference at various bias voltages may originate from the non-switchable polarization near the bottom electrode and the partially switched domain. (C) 2002 Elsevier Science B.V. All rights reserved.