The technique of Raman scattering, at room temperature, is used to investigate the effect of H2S passivation of the surface of n-type GaAs. Well-defined LO, L- and L+ features are distinguished in spectra which have been recorded in z(x, y)zBAR scattering orientation. It is observed that the ratio of the LO to L- peak is reduced by the effects of the passivation process and that the shift of the L+ feature from the laser line is decreased. This latter effect, it is suggested, is caused by a decrease in free-carrier concentration due to donor neutralization by hydrogen during passivation. This neutralization effect will also affect the LO to L- ratio and so complicate a quantitative analysis of the influence of passivation on the surface barrier potential.