Results are presented of investigations leading to the development of a procedure for the titrimetric determination of vanadium IV with potassium dichromate in a strong phosphoric acid medium (> 12M) at room temperature, using a potentiometric end-point. Cerium IV iron III, chromium III, tungsten VI molybdenum VI, uranium IV, cobalt II and nickel II do not cause any interference. Methods have also been developed for the differential potentiometric titration of iron II plus vanadium IV manganese II plus vanadium IV and iron II plus manganese II plus vanadium IV in the same solution. The new reagent thus possesses several advantages over potassium permanganate and cerium IV sulphate. Application of the new reagent to the analysis of a ferro alloy and an alloy steel is considered.