The mass attenuation coefficients for Cd, Se, Te in elemental state and semiconductor CdSe, CdTe were measured at different energies from 9.7 to 87.3 keV by using the secondary excitation method. These energies were obtained using secondary targets such as Br, Sr, Mo, Cd, In, Sn, Sb, La, Eu, Tb, Yb, W, Au, Hg, Tl, Ph, and Bi. These secondary targets were excited with Am-241 and Co-57 annular radioactive sources. X-rays emitted from secondary targets were counted by an Ultra-LEGe detector with a resolution of 0.15 keV at 5.9 keV. Effective atomic numbers and their variation with photon energy in CdSe and CdTe semiconductors were discussed. Experimental mass attenuation coefficient values were compared with theoretical values obtained using XCOM. (C) 2008 Elsevier Ltd. All rights reserved.