[en] The results of measuring the ratio of the mean capture cross section for ²³⁷ Np to the mean fission cross section for ²³⁹ Pu in two fast critical assemblies are discussed. Two activation methods, namely, the relative method of normalisation to ²³⁷ Np and ²³⁹ Pu thermal cross sections and absolute method of determining the absolute rates of capture in ²³⁷ Np and fission in ²³⁹ Pu are applied in the experiments. The results of measurements are compared with calculations and the data obtained by the reactivity method. The conclusion is made that the reactivity method being hard in interpretation gives nowadays the results which are in good agreement with the discussed results of direct integral verification of errors in ²³⁷ Np capture cross sections within the specified accuracy of ± 4%