TheK-shell ionization probability associated withα-decay and nuclear reactions involving charged particles is calculated. The monopole and dipole term of the Coulomb interaction are considered as well as the nuclear recoil. Relativistic and screening effects are neglected. The theoretical predictions are in good agreement with experiment forα-decay and 52 MeVα-particle X-ray production. A dependence of the ionization probability on the intermediate nuclear state lifetime is found. Coincidence experiments for determining nuclear time delays are discussed.