The mass attenuation coefficients for Y2O3, BaCO3, CuO compounds, and solid-state forms of YBa2Cu3O7 superconductor were determined at energies of 57.5. 59.5. 65.2, 74.8, 77.1, 87.3, 94.6, 98.4, 122, and 136 keV. The samples were irradiated using a Am-241 point source emitting 59.5 keV photon energies and a Co-57 point source emitting 122 and 136 keV photon energies. The other energies were obtained using secondary targets such as Ta, Bi2O3, and (CH3COO)(2)UO(2)2H(2)O. The gamma- and x-rays were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Samples were selected on the basis of known composition and mass densities were measured using a densitometer. The experimental results obtained in this study are compared with theoretical values.