It has been shown that a pressurized water boiling (PWB) at 2 atmospheric pressures and 120 °C in an autoclave vessel accelerates significantly hydrogenation and neutralization of B acceptors in Si. Compared with boiling at atmospheric pressure, PWB reduces more the free‐hole IR absorption and increases more the sheet resistivity in B implantedp+layer onn‐type substrate. An IR absorption of B–H stretching vibration (∼1907 cm−1) has been detected at 16 K for ap+layer which was PWB processed for only 6 h. Concentration increase of H‐related species in water and faster diffusion of H in Si at higher temperature may be the cause. In contrast with other hydrogenation techniques, water boiling hardly passivates donors in Si even for 10 h PWB. ©1995 American Institute of Physics.