We present a detailed study of calculated near edge X-ray absorption spectra using Xα multiple scattering theory. In this study we have investigated a series of simple molecules including diatomics like CO or N2 as well as polyatomic molecules (e.g. N2H4, H2CO or CH3OH). To avoid problems usually related with the ambivalent choice of muffin-tin radii we have chosen a semi-empirical approach using experimental ionization potentials to fix the radii. We will show that the qualitative as well as the quantitative agreement between experimental and calculated spectra obtained in this way is strikingly good. © 1990 Pergamon Press plc.