The first lowest (2)Pi and (2)Sigma(+) states of OCl, as well as the (1)Sigma(+) and HCl states of HCl, have been calculated at the ab initio MRCI level, and modeled semiempirically using the extended Hartree-Fock approximate correlation energy method. Spectroscopic RKR data and accurate ab initio energies have been used to obtain the model parameters. The vibrational levels of those states have also been calculated, and found to be in good agreement with existing spectroscopic data for the ground electronic states of the title diatomic molecules.