PURPOSE: To obtain a 3-alkyl-2,6-dichloroacylanilide in high efficiency and high purity by electrolyzing a bromo-alkylacylanilide and debrominating.

CONSTITUTION: Bromo-alkylacylanilide expressed by formula I is electrolyzed in a device having partitioning walls and compartments to produce 3-alkyl-2,6- dichloroacylanilide expressed by formula II. In formulae I and II, R1, R2 are each independently a 1-2C alkyl, especially methyl. Debromination is caused on the cathode of the electrolytic device, and the reaction medium in the cathode side is a 1-2C alkanol, especially methyl alcohol. A conductive material having stable and enough high hydrogen overvoltage to a halide-contg. soln. is used as the cathode. The reaction medium in the anode side is an acid or an alkali halide metal soln., and an inactive material under the reaction conditions is used as the anode.