The backscatter of normally incident bremsstrahlung spectra photons from semi-infinite materials was investigated experimentally. The bremsstrahlung sources were broad-beam radiation from a 2.0-MeV radiographic Van de Graaff and high intensity flash x-ray devices of 3.5-, 7.0-,and 10.5-MeV peak energy. The scattering media were concrete, iron, and lead. Four back scattering angles (120, 130, 140, and 150 deg) were studied. The scattered radiation was measured by means of thermoluminescent dosimeters (LiF) located in collimated shields. The experiments were designed for shielding studies and the results are presented in a form primarily for use in health protection shielding calculations.