For calculations of high-temperature gas-cooled reactors with low-enrichment fuel, it is important to know the plutonium cross sections accurately. Therefore, a calculational method was developed, by which the plutonium cross-section data of the ENDF/B-IV library can be examined. This method uses zero- and one-dimensional neutron transport calculations to collapse the basic data into one-group cross sections, which then can be compared with experimental values obtained from integral tests. For comparison the data from the critical experiment CESAR-II of the Centre d’Etudes Nucléaires, Cadarache, France, were utilized. In this experiment samples with different plutonium concentrations and different mixtures of the plutonium isotopes were oscillated inside the core at different temperatures between 20 and 360°C. The simulation of this experiment through the calculational model developed in the present study showed that the ENDF/B-IV data for plutonium are reasonable.