The molecular properties of a non-classical mesogenic polymer - poly (decamethyl-cyclohexasiloxane), and low molecular analogs of its monomer unit have been studied by electrooptical Kerr effect in solution. It was shown that every polar hexasiloxane cycle in the polymer chain acts independently under influence of external electric field. Based on the results of the study of dipole moments and electrooptical properties of low- molecular-mass cyclohexasiloxanes with different polar side-groups (CH3, -C6H5, -OH, -OC2H5) it was established that hexasiloxane cycle is able to preserve its conformation (i.e. its form and size) because of its polar properties depend weakly on the type of side-substituents. An observed stability of polar hexasiloxane cycle under the external action may be considered as responsible for the ability of poly(cyclohexasiloxanes) to form highly organized mesomorphic phases.