NEW MATERIAL:A nematic liquid crystal compound expressed by formula I (R is 1W10C n-alkyl: X is H, CH3 or Cl).

EXAMPLE: Hydroquinone ester of 1,4-bis-(5-n-butyl-2-thienylacrylic acid) expressed by formula II.

USE: One component of liquid crystal compositions, which is a thiophene based nematic liquid crystal compound capable of exhibiting the liquid crystal phase within a wide temperature range under high temperature conditions and usable in a mixture with another nematic liquid crystal compound of nonnematic liquid crystal compound.

PREPARATION: For example, a compound expressed by formula II and a compound expressed by formula III are subjected to dehydration reaction in the presence of pyridine in a solvent, e.g. dichloroethane, using a dehydrating agent, e.g. N,N'-dicyclohexylcarbodiimide, etc., to afford the aimed compound expressed by formula I in one stage.