The thermal neutron activation cross sections of Re-185 and Rwere measured and found to be 96.5 = 10 barns and 88 = 14 barns, respectively. The effective resonance integral of natural rhenium was measured to be 694 = 28 barns in cluding the 1/v component. The (n, 2n) cross sections of Re-185, Re- 187, and Re-185 (n, 2n) Re-184m with 14.1 Mev neutrons were found to be 1.91 = 0.6 barns, 1.44 = 0.41 barns and 1.12 = 0.4 barns, respectively. The (n, alpha) reaction with 14.1 Mev neutrons was investigated theoretically and it was concluded that this reaction does not occur. The (n, p) reaction was also investigated on a theoretical basis and it was found that this reaction is improbable with 14.1 Mev neutrons. The cross section of this reaction was calculated to be 32.2 millibarns. This calculation, however, could be in error by a factor of 10. The decay scheme of Re-184 Re-184m is proposed and the gamma rays from Au-196 and Au-196m were studied. Comparison of the shielding properties of rhenium and lead for thermal neutrons was made on a theoretical basis. A technique for separating gamma ray pulses from neutron pulses in NaI (T1) detectors is also included.