[en] A new method for determining oxygen in potassium is investigated. The potassium matrix is separated by vacuum distillation at the temperature of 250 degree C and under the vacuum of 6 x 10^-4 Pa. The residue is dissolved. Volumetric analysis is used to analyse oxygen in the residue. Average deviation of determined samples is <15%. This method has been applied to determine the concentration of oxygen in potassium when Na-K alloy was compounded. When potassium is cleaned, this method can also be applied to determine oxygen in potassium. (authors)