The new radiation method for the determination of impurity anions in insoluble oxysalts is described. The analysis includes: (1) The irradiation of salts containing impurity anions at room temperature, (2) determination of maximum concentrations of impurity paramagnetic centers formed which are close to impurity anion concentration in the range of 10−3 up to 10−1 mole%. The method is valid for those anions whose ionization potentials are lower than the corresponding ionization potentials of the matrix.