[en] Calculations of the average neutronic properties of the ensemble of fission products producted by fast-neutron fission of ²³⁵U and ²³⁹Pu, where the properties are determined before the first beta decay of any of the fragments, are described. For each case we approximate the ensemble by a weighted average over 10 selected nuclides, whose properties we calculate using nuclear-model parameters deduced from the systematic properties of other isotopes of the same elements as the fission fragments. The calculations were performed primarily with the COMNUC and GNASH statistical-model codes. The results, available in ENDF/B format, include cross sections, angular distributions of neutrons, and spectra of neutrons and photons, for incident-neutron energies between 10^-5 eV and 20 MeV. Over most of this energy range, we find that the capture cross section of ²³⁹Pu fission fragments is systematically a factor of two to five greater than for ²³⁵U fission fragments