  Electron spin resonance (ESR) spectra of Fe3+ and Mn2+ ions have been studied
in the nominally pure and 0.05% Li-doped single crystals of CdWO4. The
zero-field splitting parameters are determined with a high precision for both
of the impurities. The result suggest that the Li-doping leads to the increase
of the ionic charge of iron from 3+ to 4+ and of manganese, from 1+ to 2+.
