A compound N-.beta.(2-acetyl-4-chlorophenoxy)-ethyl-N,N-dimethyl-N-benzylammonium-p-c hlorobenzene sulphonate having the formula: ##SPC1## This compound is prepared by reacting 2-hydroxy-5-chloroacetophenone and .beta.-dimethylaminoethyl chloride with heating in a medium of an organic solvent in the presence of an alkali agent, reacting the resulting 2-acetyl-4-chlorophenoxyethyl-dimethylamine with benzyl chloride, and subsequently reacting the resulting N-.beta.-(2-acetyl-4-chlorophenoxy)-ethyl-N,N-dimethyl-N-benylammonium chloride with a sodium salt of p-chlorobenzene sulphonic acid. This compound exhibits anthelmintic activity for Trichocephalus muris in albine mice.