The effective atomic numbers (Z(eff)) and effective electron density (N-e) for three different steels have been determined via the mass attenuation coefficients (mu/rho). The mass attenuation coefficients have been calculated at the photon energy range of 1 keV-1 GeV and measured at the photon energies of 662, 1173 and 1332 keV. The measurement has been performed using a gamma spectrometer that contains a Nal(Tl) detector connected to Multi-Channel-Analyzer (MCA). The measured results of effective atomic numbers (Z(eff)) and effective electron density (N-e) were found to be in good agreement with the calculations. (C) 2009 Elsevier Ltd. All rights reserved.