An ab initio pseudopotential method is used to investigate the Structural and phonon Properties of SO and ScAs in the B1(NaCl) structure. The calculated lattice constants, static bulk modulus and first-order pressure derivative of the bulk modulus are reported in B I structure and compared with previous calculations. A linear-response approach to the density-functional theory is used to derive the phonon frequencies and density of states. The phonon dispersion curves for the two materials are compared. (c) 2008 Elsevier Ltd. All rights reserved.