The demand has increased for a high‐current, long lifetime ion source in various fields of application. The present work concerning the production of atomic hydrogen ions H+ in competition with molecular ions H+2 has been essentially motivated by recent trends in the field of passivation of silicon [V. Le Thanh, M. Eddrief, and C. A. Sébenne, Appl. Phys. Lett. 64, 3308 (1994)]. For a given low neutral energy, passivation with a neutral atomic beam H instead of H2 is preferred. The most straightforward method to produce the neutral beams is by the extraction of low energy atomic ions, and neutralization by electron capture. We have thus developed an electron cyclotron resonance coaxial hydrogen ion source that produces a 30‐mm‐diam ion beam, is operated with a microwave power in the range of 50–130 W, and has a pressure of neutrals in the range of 6×10-4–4×10-3 mbar. We have compared the proportion of extracted H+ and H+2 ions with the two principal parameters of the plasma: the pressure of neutrals and microwave injected power. These parameters have been optimized for the production of an 83% atomic ion beam. © 1996 American Institute of Physics.