The document describes a method for the determation of the concentration of nuclear grade Pu and Pu/U solutions, with known isotopic compositon in nitric or sulfuric acid. It is used for Pu concentrations above 1 g/l. For the titration, 6 - 50 mg Pu are required. After dissolving in nitric or sulfuric acid, Pu can also be determined in solid PuO2 or PuO2/UO2 samples.#,,#