The ratio of resonance integral to thermal activation cross sections of the isotopes 64Zn, 68Zn, 85Rb, 100Mo, 102Ru, 113In, 123Sb, and 180Hf relative to gold has been determined by measuring cadmium ratios.The standard gold or a secondary standard was mixed uniformly in the samples and the activities resolved with a lithium-drift germanium γ-ray spectrometer. Expressed as Westcott S0 values the results were: 64Zn = 2.06 ± 0.03, 68Zn = 3.72 ± 0.14, 85Rb = 18.4 ± 0.6, 100Mo = 21.7 ± 0.8, 102Ru = 3.76 ± 0.03, 113In = 24.7 ± 0.5, 123Sb = 28.3 ± 2.1, 180Hf = 2.17 ± 0.09. All measurements are relative to S0 = 17.7 for gold.