Ferroelectric materials are rather exactly specified for small signal application by their linear elastic, dielectric and electromechanical coefficients. However, an unambigeous characterization cannot be given by these means if a high mechanical or electrical power level is applied. Further the study of the large signal behaviour is important for the understanding of structural phase transitions of ferroelectric materials (ceramics, crystals and thin films). The aim of the present paper is to show that the application of methods of nonlinear dynamics, e.g. spectrum-and time series analysis, is a useful tool for studying this large signal behaviour . Investigations concerning the nonlinear behaviour of ferroelectric materials were performed in a wide range of parameters of a driven series resonance circuit. The bifurcation cascades, the periodic and chaotic phase portraits and the Poincar6 sections were used for the determination of the nonlinear coefficients of the sample.