The degree of dissociation of molecular hydrogen in a RF parallel plate plasma reactor is analyzed by three different emission spectroscopic methods. These schemes are based on the comparison of line intensities of atomic and molecular hydrogen and of argon which is admired as a tracer gas (actinometry). The different schemes yield similar results in the parameter ranges where they are applicable. The basic assumptions, the available cross sections, and the conditions and limitations of applicability of the different schemes are compared and discussed.