The dielectric absorptions observed on six poly (thiocarbonates) (PTC) containing different substituents in the interphenylic carbon atom are subjected to a study. The a relaxation process associated with the glass transition temperature, which appears at the highest temperature studied, is overlapped with a strong conductive component. Between 80 and 100-degrees-C dielectric activity (beta) is observed, which is related to structural relaxation phenomena. Polymers with double substitution on the interphenylic carbon atom show a gamma relaxation with an activation energy of ca. 11 kcal mol-1 while those where the carbon atom is linked to a cyclohexyl group show higher activation energies and their respective characteristics. A cryogenic absorption around -120-degrees-C, for at least three polymers with an activation energy of about 5 kcal mol-1, is detected.