The total mass attenuation coefficients (μ/ρ), for GaAs, GaAs (semi-insulating; S-I) GaAs:Si (N + ), GaAs:Zn, InP:Fe, InP:Fe–As, InP:S and InP:Zn crystals were measured at 22.1, 25.0, 59.5 and 88.0keV photon energies. The samples were irradiated with 109 Cd and 241 Am radioactive point sources using transmission arrangement. The X- and γ-rays were counted by a Si (Li) detector with resolution of 160eV at 5.9keV. Total atomic and electronic cross-sections (σ t and σ e ), effective atomic numbers (Z eff ) and electron densities (N el ) were determined using the obtained μ/ρ values for the investigated crystals.