A mesomorphic compound of the formula (I) according to Claim 1 and an optically active compound of the formula (II) according to Claim 2 are suitable as a component for a liquid crystal composition providing improved response characteristics and having an improved helical pitch at a cholesteric phase or a chiral smectic C phase. The above liquid crystal composition is useful as an element of a liquid crystal device providing a good display characteristics including a gradation display.