Abstract: A complex salt of a thiodiphenylamine cupric chloride of the formula: ##STR1## The process for producing said salt comprises reacting an aqueous solution of cupric chloride with thiodiphenylamine in a stoichiometric ratio of said cupric chloride and the thiodiphenylamine; the pH is from 2 to 2.5 and the temperature within the range of from 10.degree. to 90.degree. C. The precipitate of the desired product is separated from the mother liquor and dried. In order to reduce the acidity of the product being produced, the solution may be neutralized, prior to the separation of the precipitate, with a sodium or potassium carbonate or hydroxides of the said metals to a pH of from 7 to 8.The complex salt of thiodiphenylamine cupric chloride possesses pharmacological activity and is useful in veterinary medicine as a helminthicide for treating helminth infestation diseases of farm animals. In addition, said salt may be used in agriculture as an insecto-fungicide.