Developing a well accepted method for piezoelectric characterization of piezoelectric thin/thick films is an essential issue in the research of piezoelectric micro-electromechanical systems. This article presents a scanning interferometric technique for piezoelectric characterization of lead zirconate titanate (PZT) thin/thick film on silicon substrate. This technique is established using a newly developed scanning Mach-Zehnder interferometer with ultra-high resolution. The apparent longitudinal piezoelectric coefficients of both sol-gel derived PZT thin films and hybrid PZT thick films are measured using the scanning technique. The roles of several film processing factors on the piezoelectric properties of the resultant films are also discussed. (c) 2005 Elsevier B.V. All rights reserved.