The C 1s x-ray photoelectron spectroscopy binding energies of a series of organic (CO, CH 4 , C 2 H 2 , HCHO, CH 3 CCH, C 6 H 6 ) and inorganic [Ni(CO) 4 , Mo(CO) 6 ] molecules have been calculated by using the linear-combination of Gaussian-type orbitals local- and nonlocal-spin-density (LCGTO-LSD and LCGTO-NLSD) methods. The calculated C 1s chemical shifts are in very good agreement with experiment. The differences between experimental and theoretical shifts are found to be less than 0.5 eV. It is shown that the addition of nonlocal corrections improves the agreement with the experimental data