The spectrometric characteristics of zinc-selenide-based scintillators under alpha, beta, and gamma excitations have been investigated. The optimal conditions of signal collection for energy resolution measurements have been determined. The resolution of ZnSe(O)-Si-PD (PD = photodiode) for alpha particles ($^{239}$Pu, E = 5.15 MeV) is 3.1 \%; for the beta particles ($^{207}$Bi, E = 976 keV), it is 3.7 \%; and for gamma quanta ($^{137}$Cs, E = 662 keV), it is 6.3 \%. High light output, satisfactory energy resolution, and an $alpha/gamma$ ratio which close to one allow for application of ZnSe-based scintillators for alpha particle, beta particle, and gamma quanta identification.