4-Amino-4'-chlorodiphenyl, a related compound of benzidine, is used as a reagent for sulfate determination, hence it is interesting to study whether this reagent can be used as a precipitant in tungsten(Ⅵ) and molybdenum(Ⅵ) determinations.It is found in the present investigation that the reagent may be used as a precipitant for tungsten(Ⅵ) and is promising for molybdenum(Ⅵ) determinations.