The effects of hydrogen implantation on the structural and electrical properties of nickel silicide have been investigated. Ni films (30 nm) are electron-beam-evaporated on Si substrates, after which plasma immersion ion implantation is used to introduce hydrogen ions into the Ni films at an energy of 350 eV to a dose of 1 x 10(16) cm(-2). For nickel silicidation reactions, rapid thermal annealing is carried out in the range of 400-750degreesC for 30 s in a nitrogen atmosphere. It is shown that the implanted samples produce lower sheet resistances than the unimplanted samples across the whole annealing temperature range. X-ray diffraction results show that, regardless of the hydrogen implantation, NiSi is transformed into NiSi2 at temperatures in excess of 700degreesC. X-ray photoemission spectroscopy results show that the hydrogen implantation plays a role in reducing the nickel oxide layer. Compared to the unimplanted samples, the implanted samples exhibit better surfaces and uniform NiSi/Si interface morphologies. Transmission electron microscopy results show that the grain sizes of the implanted sample are smaller than those of the unimplanted sample. It is further shown that the implanted samples are thermally more stable than the unimplanted samples, which is attributed to the difference in the grain sizes of the nickel silicide films.