The mass attenuation coefficients for Bi, Pb, Sr, Ca, Cu metals, Bi2O3, PbO, SrCO3, CaO, CuO compounds and solid-state forms of Bi1.7Pb0.3Sr2Ca2CU3O10 superconductor were determined at 57.5, 65.2, 77.1, 87.3, 94.6, 122 and 136 keV energies. The samples were irradiated using a (CO)-C-57 point source emitted 122 and 136 keV gamma-ray energies. The X-ray 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 0.16 keV at 5.9 keV. The effect of absorption edges on electron density, effective atomic numbers and their variation with photon energy in composite superconductor samples was discussed. Obtained values were compared with theoretical values. (c) 2007 Elsevier B.V. All rights reserved.