NEW MATERIAL:The compound of formula I (X is halogen; Y is H or halogen; R is H, straight-chain lower alkyl group, branched lower alkyl, lower alkyl interposed with hetero atom or carbonyl group, etc.).

EXAMPLE: 2-Nitro-5-(2'-chloro-4'-trifluoromethylphenoxy)phenylglyoxaldoxime.

USE: A herbicide effective remarkably to Deccan grass which is a harmful gramineous weed in paddy field. It has no phytotoxicity to paddy rice plant, and exhibits satisfactory herbicidal effect at a low rate of application.

PREPARATION: The compound of formula I can be prepared by (1) nitrosating the acetophenone derivative of formula II with an alkyl nitrite, etc. in an inert organic solvent, (2) dissolving the obtained derivative of formula III in an alcohol, etc. to produce a base such as sodium methylate, and (3) reacting with the compound of formula Z-R (Z is halogen, etc.) at 0W100°C.