Number of dimethyl and diphenylsiloxane polymers as well as siloxane copolymers were prepared and blocked using trimethyl and triphenyl dichlorosilanes. Moreover, a new series of graft copolymers, in which polyol was used, were also prepared. The new compounds were characterized using different spectroscopic techniques [Fourier Transform-Infrared Spectroscopy (FT ir), Ultraviolate Spectroscopy (U.V)]. Relative molecular weights of these compounds were determined from linear relation between mole ratio and intrinsic viscosity, as well as electrical properties were through density, specific conductivity, refractive dielectric constant correlation, as well as thepolarizability and dipolemoment of these compounds were and studied. Thermal properties of these compounds were alsostudied [Glass Transition Temperature (Tg), melting Temperature (Tm), Crystalization Teperature (Tc) using differential scanning calorimetry (DSC) It was found that phenyl derivatives are more stable than methyl analogous.