Hot atom chemistry /Potassium selewte Z^5 Se /Impurity effects AbstractThe influence of the dopant cations Al 3+ , In 3+ and Ca 2+ on both thermal and gamma-annealing in neutron-irradiated K 2 Se0 4 has been studied. Assuming that the introduction of the dopant cations, M n+ , in the lattice leads to the creation of both M^* sites and K + -vacancies, Q k+ , the effect of the impurity on the initial retention is explained in terms of the overall efficiencies of these species for hole-capture, at a given temperature. Hole release from 33 K + on heating after irradiation should account for the changes brought about by the dopants in the experimental isochronal annealing curves. Simple kinetic models are proposed and calculated curves are shown as an illustration.