Damage depth profile and thermal recovery characteristics of 16 MeV proton irradiated 12Cr-1MoV steel (approximately 2 x 10(18) p/cm2, irradiation temperature < approximately 398 K) were investigated by Vickers microhardness measurement, thermal annealing experiments and TRIM 90 computer calculation. A damage depth profile estimated by Vickers microhardness in depth showed a relatively similar profile trend to the result of calculation but the hardness peak appeared nearer to the surface and the half-value width was broader in the hardness profile than in the calculation. The isochronal anneal showed two recovery stages. The recovery activation energies were 1.4 and 1.5 eV for the recovery stage 1 and 2, respectively. The order of reaction was about 1 and isothermal recovery behavior showed a relatively good agreement with characteristic rate constants for both recovery stages. From the recovery activation energy and order of reaction, it was estimated that defects of low recovery activation energy were formed upon irradiation: presumably, carbon and/or hydrogen stabilized vacancy type defects.