A method of scanning photodielectric spectroscopy of crystals has been suggested. It is based on the measurements of small increments of the real ΔЄ′ and imaginary ΔЄ″ parts of effective dielectric permittivity at a smooth variation of the photoexcitation wavelength λ. The spectral functions ΔЄ′(λ) and ΔЄ″(λ) are presented in a complex plane, that is, in parametric view, and their characteristic points are determined. Application of this method on Cd1-xZnxTe crystals showed a possibility of determining the energy position of the localized states generated in the forbidden zone by the intrinsic structure defects. © 2002 American Institute of Physics.