Swelling, hydride composition. distributions of microhardness and thermoelectric power in cross sections of zirconium hydride samples irradiated in the BN-600 reactor with neutron fluence of similar to 6.0.10(26) n/m(2) (E > 0) in the temperature range of 670-770 K have been investigated, A correlation of microhardness increment and swelling has been established. Swelling in outer layers of materials turned out to be twice of that in inner ones. This fact is due to variations of neutron flux and energy release-radiation heat generation ina bulk of zirconium hydride under fission gamma ray and neutron irradiations.