Hydrogenated amorphous silicon thick films deposited by dc glow discharge on molybdenum substrates were annealed by a pulsed Nd:glass laser. Mass spectrometry showed hydrogen remaining in all the laser annealed films. The amount of hydrogen remaining decreased with decreasing scan rate. The hydrogen evolved upon heating at 365 °C and mainly at 658 °C before laser annealing, but at 365, 575 (Mainly) and 645 °C after laser annealing, indicating weakening of the silicon-hydrogen bonding after laser annealing. The presence of hydrogen inhibited crystallization, as indicated by Raman scattering. The photo and dark conductivity of the film increased by one and three orders of magnitude respectively with increasing laser energy density up to 12 J/cm2 at a fixed scan rate. This Means that the photoresponse was decreased with laser annealing, in spite of the associated increase in crystallinity. This photoresponse decrease is attributed to the hydrogen evolution.