H + ion implanted SOI structures formed by hydrogen ion cut have been investigated by SIMS, Raman spectroscopy and photoluminescence (PL). After implantation the wafers have been heat-treated by either furnace annealing or rapid thermal annealing. It has been found that implantation of 1x10 1 7 to 3x10 1 7 H + /cm 2 results in the formation of the amorphous Si layer (a-Si) inside silicon film on insulator. Structural transformations in a-Si depended on the annealing conditions. Furnace annealing (FA) led to crystallization of a-Si and to the formation of monocrystalline silicon films. Rapid thermal annealing (RTA) results in the formation of the layers containing a high density of Si nanocrystals. A comparison of the Raman measurements with the PL data allows us to conclude that PL bands obtained near 420 and 500 nm are not associated with the radiative recombination in Si nanocrystals.