Abstract A first-principles, self-consistent computational approach for determining the electronic properties of chain polymers has been developed. The local-density functional formalism in conjunction with a linear combination of atomic orbitals approximation using a Gaussian basis can then be used to calculate band energies and one-electron wave functions for chain polymers. Using perturbation theory, these results can be used to calculate theoretical x-ray and ultraviolet photoelectron spectra. Calculations have been performed for polyacetylene and the heterocyclic ring chain polymers. The resulting photoelectron spectra for polyacetylene are shown to be in excellent agreement with experiment. In addition, a theoretical prediction is made for the photoelectron spectra of polythiophene.