FeRh and Ni3V intermetallic compounds were irradiated with 16MeV Au5+ ions and were subsequently annealed at elevated temperatures from 100 to 500 °C. The non-thermal equilibrium A1 and L10 phases of FeRh, which were caused by the ion irradiation, disappeared by 300 °C-100 min annealing. The non-thermal equilibrium A1 phase of Ni 3V caused by the ion irradiation disappeared by 500 °C-100 min annealing. The Vickers hardness for these two intermetallic compounds changes during the thermal annealing in a direction opposite to its change by the irradiation. The present experimental result shows that the combination of energetic ion irradiation and subsequent thermal annealing can be used as a useful tool for the modification of the mechanical properties of FeRh and Ni3V intermetallic compounds.