Simultaneous vibro-rotational analyses have been carried out for the second positive system (SPS) of N 2 ( C 3П u − B 3П g ), for the violet system (VS) of CN ( B 2Σ − X 2Σ) and for the Swan system (SS) of C 2 ( d 3П g − a 3П u ), emitted by 35 MHz electrical discharges, containing N 2, H 2 and CH 4 flowing mixture s, in the 5–40 torr pressure range and at 1–10 Wcm -3 power densities. The results are consistent with a Boltzman distribution for the rotational levels, but they show a deviation from this law for upper vibrational levels of CN and C 2.