We studied the effect of neutron irradiation on composite material HfC-HfB2-C made using rapid reactive hot pressing technology. The histograms of microhardness and results of X-ray phase analysis, obtained both before and after neutron and electron irradiation of the samples, were considered. It was found that secondary electrons make a considerable contribution at low-fluence (~1014 neutron/cm2) neutron irradiation. A fluence range was determined at which reduction of composite material microhardnessis observed.