Poly(3-alkylthiophene)s was proved to be perspective materials for molecular electronics. The charge is carried by non-linear excitations, polarons, in these organic semiconductors. Polaron possesses spin S = 1/2, therefore EPR spectroscopy is one of powerful method studying such paramagnetic impurities in organic polymer semiconductors of lowed dimensionality. The present report is devoted to the data obtained in the study at different (10 - 140 GHz) wavebands EPR of magnetic, relaxation and dynamics parameters of charge carriers in various poly(3-alkylthiophene)s. High spectral resolution achieved at 2-mm waveband allows one to register all components of anisotropic g-factor of such paramagnetic centers, so then to analyze magnetic, relaxation and dynamics properties of charge carriers differently oriented in an external magnetic field. The method of steady-state saturation of spin packets was used for determination of relaxation and diffusion rates for paramagnetic centers. The superslow anisotropic molecular dynamics in poly(3-alkylthiophene)s was investigated by the saturation transfer (ST-EPR) method. Spin and charge transfer was shown to correlate with molecular dynamics in poly(3-alkylthiophene)s. The mechanism of charge and spin transport in the systems under study was ascertained to depend on the structure of polymer semiconductor. Reversible charge transfer from polymer chain to fullerene was investigated by light-induced EPR method. Therefore, multifrequency EPR spectroscopy allows one to obtain more information on magnetic, relaxation and electronic parameters of low-dimensional semiconductors with different heteroatoms.