PURPOSE: To provide a mixture of trans-4,4'-n-dialkylazoxybenzene isomers, having broad nematic liquid crystal temperature range, and useful as a matrix-driving twisting nematic liquid crystal display.

CONSTITUTION: A mixture of the trans-4,4'-n-dialkylazoxybenzene isomers of formula I (R1 and R2 are 1W10C straight-chain alkyl; R1≠R2). The mixture of formula I is obtained by preparing the isomers of the formula II and the formula IIIseparately, and mixing the isomers at a desired ratio. Although each of the compounds of formula I and II has broad nematic temperature range, the range can be further broadened by mixing the compounds with each other. It has excellent dynamic characteristics and is expected to be suitable as the base of a matrix-driving liquid crystal composition. It has remarkably improved light- resistance.