The possibility of applying the spin probe and label method to the investigation of semiconductive polymer materials at 2 mm waveband EPR has been shown. Advantages of this method in the study of polymer structural, conformational and electrodynamic characteristics have been exemplified by polypyrrole modified by nitroxide radicals as a probe. The distance between nitroxide radical and spinless charge carriers on polymer chain, effective dipole momentum and size of spinless charge carriers as well as the bipolaronic charge transfer mechanism in doped polypyrrole have been determined. The use of the spin probe and label method with a high spectral resolution EPR technique has permitted a detailed analysis of mobility, nature and size of charge carriers in polymer semiconductors