PURPOSE: To obtain the titled compound which is an ultraviolet light absorber in high yield without problem in economy and pollution, by reducing an o-nitroazobenzene with a primary or secondary alcohol in the presence of a hydrogen transfer catalyst and a base.

CONSTITUTION: An o-nitroazobenzene of formula I (R1 is H, Cl atom, 1W4C lower alkyl, 1W4C lower alkoxyl, etc.; R2 is H, Cl atom, 1W4C lower alkyl or 1W4C lower alkoxyl; R3 is H, Cl atom, 1W12C alkyl, 1W4C lower alkoxyl, etc.; R4 is H, Cl atom, hydroxyl, etc.; R5 is H, 1W12C alkyl, etc.) is reduced with a chemical equivalent amount or more of a primary or secondary alcohol in the presence of a hydrogen transfer catalyst, e.g. anthraquinone, and a base and further preferably a phase transfer catalyst, surfactant or polyhydric alcohol to give the aimed compound of formula II.