Charge exchange between low-energy ions and solid surfaces has been discussed with particular emphasis placed on the effects of valence orbital hybridization on the electronic transition probability. Two examples are presented, i.e., resonance neutralization of He + and H + scattering. The He + ions are neutralized very efficiently at a specific surface of graphite, because the He 1s orbital satisfies the resonance condition with the C sp 2 band and the vacancy can immediately diffuse into the band during the collision time with the target C atom. Neutralization of the hydrogen ion at a surface is rather unique compared to the He + ions and its probability is sensitively dependent upon ionicity of target atoms or the nature of the valence band. It is concluded that H + captures a valence electron via a new class of resonance neutralization process which is mediated by a short-lived chemisorption state of hydrogen.