A long thin bar of SrTiO3 exposed to a large dc field exhibits a transverse electromechanical resonance even after the dc field is turned off. In addition, its capacitance is lowered irreversibly and there is pyroelectricity. All these phenomena are treated in the light of a model involving layer structure of the sample induced by the application of a transient dc field. It is shown that a surface layer of about 4μ thickness exhibits piezoelectricity and a dielectric constant much lower than that of the bulk, due to trapping of a strong electric field near the surface. © 1974, Taylor & Francis Group, LLC. All rights reserved.