This paper reports the investigation result of RF power effects on the RF hydrogen plasma parameters. The hydrogen plasma parameters are measured experimentally in the center of the deposition chamber by means of the cylindrical Langmuir probe. The measurements are done at 0.2 mbar hydrogen gas pressures. The applied discharge powers are between 50 W and 200 W. It is found that the electron and ion densities increase with the RF power. The ion density dependence of the cathode sheath voltage is fitted to N_i(cm^-3)=-3.5 10¹⁰ + 9.2  10⁷ (V_o - V_dc). The plasma and floating potentials are less sensitive to RF power.