The influence of dissociation of Hz(v) molecule at vibrational levels in the range 10-14 through collisions with H-2 and H on the vibrational distribution function (vdf) and the dissociation yield of H-2 in microwave sustained reactors has been investigated using recent theoretical estimations of the dissociation rates based on semi-classical trajectory method, The results show that insertion of H-2(v = 10-14) strongly affects the dissociation process leading also to a non-Boltzmann vdf of H-2(v).