Femtosecond laser treatments (second harmonic of Ti-sapphire laser, λ ≈ 400 nm wavelength, 30 fs pulse duration) were applied for crystallization of thin hydrogenated amorphous silicon films on glass substrates. The concentration of atomic hydrogen in the films was varied from 10 to ≈35\%. The energy densities (laser fluences) for crystallization of the films with thicknesses from 20 to 130 nm were found. Assumedly, non-thermal processes (plasma annealing) take place in phase transition caused ultra-fast pulses. The developed approach can be used for creation of polycrystalline silicon films on non-refractory substrates.