NEW MATERIAL:Biphenyl ester of formula I (R is C4W8 straight-chain alkyl).

EXAMPLE: 4-(4-Cyanophenyl)benzoic acid 4'-n-hexyloxyphenyl ester.

USE: Liquid crystal having excellent stability, positive dielectric anisotropy and a broad temperature range of liquid crystal.

PROCESS: For example, 4-bromobiphenyl is allowed to react with acetyl chloride in the presence of A1 chloride to give 4-acetyl-4'-bromobiphenyl, which is then reacted with Br2NaOH to afford 4-bromobiphenyl-4'-carboxylic acid. Treatment of the compound thus obtained with CuCN gives 4-cyanobiphenyl-4'-carboxylic acid which is then made to react with thionyl chloride to give 4-(4-cyanophenyl) benzoic acid. Finally this compound is made to react with 4-n-hexyloxyphenol to afford the objective compound of formula I