a survey of the ionoluminescence of a large number of ion-phosphor combinations under uniform conditions has been made. powdered phosphors and scintillation crystals with different activators, different methods of surface treatment and different particle size were studied in the energy range from 3—100 kev. l, the ratio of integrated photomultiplier output to incident ion current, was found to be a sensitive function of ion energy. it increased with increasing ion energy and decreased with increasing ion mass. a nonlinear relationship between l and e, the ion energy, was observed for heavier ions, the nonlinearity increasing with ion mass. comparisons of l values obtained in zns, yv04 and in zn2si04:mn phosphors of different particle size and with different activators were made. the results indicated that the light output may depend on the mechanism of luminescence, the crystal structure and the activaactivators, as well as the surface conditions of the samples. by taking into consideration the non-radiative surface recombination of electron hole pairs and assuming that the rate of generation of carrier pairs along the path of a particle is proportional to the specific energy loss in electron collision (de/dr)e, a formula was obtained to predict the nonlinear dependence of l at low energies.