The potential energy curves for neutrals and multiply charged ions of carbon monosulfide are computed with highly correlated multi-reference configuration interaction wavefunctions. The correlations of inner-shell electrons with the scalar relativistic effects are included in the present computations. The spectroscopic constants, dissociation energies, ionization energies for ground and low-lying excited states together with corresponding electronic configurations of ions are obtained, and a good agreement between the present work and existing experiments is found. No theoretical evidence is found for the adiabatically stable CS q+ (q > 2) ions according to the present ab initio calculations. The calculated values for 1st-6th ionization energies are 11. 25, 32.66, 64.82, 106.25, 159.75, and 224.64 eV, respectively. The kinetic energy release data of fragments are provided by the present work for further experimental comparisons.