The results of an investigation at different (10–140 GHz) wavebands EPR of magnetic, relaxation and dynamics parameters of mobile paramagnetic charge carriers (polarons) in low-dimensional solid-state poly(3-alkylthiophenes) semiconductors are discussed. At high registration frequency all components of the g-tensor of polarons are registered. Relaxation and diffusion rates of such paramagnetic impurities are determined by the method of steady-state saturation of spin packets