Abstract: The content of barium in baryte ores has been determined using 14. 7MeV neutron activation "relative" method. The neutron-flux is monitored by BF3 neutron-flux instrument. The neutron energies are determined by the method of cross section ratios for the reactions90Zr(n,2n)89'Zr by 93Nb(n,2n)92Nb.