The Balmer &bgr; and &ggr; line shapes have been analyzed to determine the relative density and the temperature of hydrogen atoms in magnetic multicusp plasma generators. Results for a 90 V, 4–40 mTorr, 1–18 A conventional multicusp plasma generator and a 50 V, 4 mTorr, 1–15 A hybrid multicusp plasma generator are presented. The relative number density of hydrogen atoms increases smoothly with pressure and discharge current but never exceeds 10%. The absolute atomic number density in a 90 V–10 A discharge varies in proportion with pressure. The atomic temperature (in the 0.1–0.4 eV range) decreases with pressure and slowly increases with the discharge current. The role of atoms in the processes determining the H−temperature and the H2vibrational and rotational temperatures is discussed. The results confirm that in multicusp negative ion sources collisional excitation of ground‐state atoms and molecules by energetic electrons is the dominant process in Balmer &bgr; and &ggr; light emission.