Electron paramagnetic resonance (EPR) is widely used in the study of magnetic and electronic dynamic properties of organic polymeric semiconductors (OPS). As a rule such study are carried out at registration frequencies not exceeding 10 GHz that leads to overlapping of spectral components of a composite EPR spectrum of OPS and, thus, to their incorrect and inexact interpretation. The selfdescriptiveness and precision of the method increases essentially at study of OPS at 2-mm registration waveband (150 GHz). At 2-mm waveband EPR the magnetic, relaxation and electronic dynamic parameters of poly(3-octylthiophene) (P3OT) and poly(bis-alkylthioacetylene) (PBATA) have been studied. It was shown that the shape of EPR spectrum essentially depends on a position of a sulfur heteroatom concerning a backbone of conjugation. The method of continuous microwave saturation was used for determination of the spin-spin and spin-lattice relaxation times of paramagnetic polarons, and also of their diffusion rates along and between polymeric chains of these samples. The mechanism of charge transfer in P3OT and PBATA has been identified. It was shown that the modification of the polymers leads to essential change of relaxation and electronic dynamic properties of the polymers under study.