Dielectric and electro-optical properties of the various antiferroelectric and ferrielectric smectic phases of two compounds of the homologous series MHPnCBC (n= 8,9) have been investigated. MHP9CBC exhibits an unidentified chiral induced SmC subphase (denoted by SmCx*) and shows the phase sequence Cr - SmIA* - SmCA* - SmCγ* - SmC SmCx* - SmC SmCx* - SmA - I. The electro-optical and dielectric properties of the SmC SmCx* phase of MHP9CBC differ distinctly from that of the SmC SmCα* as well as the SmC SmCγ* phase. The electric field - temperature phase diagram was obtained by two methods, measurement of the apparent tilt angle as well as the dielectric loss. The results of both methods are in good agreement. For both compounds a field induced ferrielectric state is observed in a broad temperature range (≊ 10 K) of the SmC SmCA*−phase.