We performed Hall-effect measurements as a function of temperature on lightly doped polysilicon films. The range of boron concentration encompassed a mobility minimum and a corresponding barrier height maximum. Upon plasma hydrogenation, these two extrema shifted to a lower concentration, clearly indicating a passivating effect. Spin resonance measurements on intrinsic films showed a reduction in unpaired spins after plasma hydrogenation. Desorption experiments confirmed the presence of hydrogen in the plasma treated samples.