The study is about the effect of H2 addition into N2 on the density of radiative species in the plasma and in the late afterglow of microwave flowing discharges at low gas pressure (2–10 torr). Intensities of radiative N2(B, C), N2+(B) neutral and ion molecules, H atoms and NH radicals were measured in the plasma and in the late afterglows for the N2(B) state. The results are discussed from the main kinetic reactions in the N2-H2 plasma and afterglow. From the intensity of N2, 1st pos. at 580 nm and after calibration by NO titration, the N-atom density in the afterglow can be determined. The variations of the N-atom density with H2 into N2 in the late afterglow are examined for several gas pressures (2–10 torr) at fixed microwave power (100 W) and flow rate (1 slm). The activity of the late afterglow has been measured on paper surfaces, outlining the influence of a few H2 into N2.