[en] The project seeks to study the charge capture reactions of C⁺ and O⁺ in various gases (principally H₂ and He) to determine the difference between cross sections for the ground and metastable excited states of the projectile species. Emphasis is on very low energy collisions close to threshold and data in practice extends over collision energies from 10 to 500 eV; comparison can be made with data from other sources at higher energies. In general terms cross sections for the metastable species are higher by a factor of ten than for the ground state at low energies (10 eV), are surprisingly invariant with energy, are approached by the ground state cross sections at about 10⁵ eV, after which both cross sections fall. We have shown also that the metastable content of C⁺ and O⁺ fluxes produced by dissociative ionization of various carbon containing molecules is 15 to 30%. We conclude that in the consideration of a situation involving neutralization of C⁺ and O⁺ (as for example in the edge of a fusion plasma) the metastable content may be high and will influence the net cross section significantly. Present data are not always in agreement with previously published results