The first results of K - O melt inelastic neutron scattering investigation are presented. The experiment was carried out on pure potassium at the temperature of 550K. From the analysis of potassium inelastic neutron scattering the frequency spectrum of atomic vibrations is obtained. The quasi-elastic neutron scattering data are used for obtaining the information of potassium self-diffusion process. 14 refs.; 6 figs.