Electrical birefringence in solutions of fractions and samples of cellulose acetobenzoate (CAB) with M = 1.1·104 - 1.3·106 in dioxane has been studied. From the dispersional curves of electrical birefingence obtained in sinusoidal-impulse fields in the 103-106 Hz frequencies range times of the orientational relaxation τ of CAB molecules were determined. From the τ(M) dependence using the theory of the rotational friction of kinetically rigid worm-like chains the length of the Kuhn segment was evaluated: A = (300±100)·10-8 cm. From measurements in rectangular-impulse fields the equilibrium values of Kerr constants K were determined being negative in all the M range alike the dynamic birefringence case. The discussion of the K(M) dependence from the view-point of the theory of electrical birefringence of worm-like chains permitted to conclude its dependence on the longitudinal components of the monomer units dipoles μ0∥ with minimal contribution of normal components. From the K(M) dependences the length of the