In this work we calculate the mass spectra of charmonium for 1P; …; 4P states of 0 þþ and 1 þþ , for 1S; …; 5S states of 0 −þ , and for 1S; …; 4D states of 1 −− along with the two-photon decay widths of the ground and first excited states of 0 þþ quarkonia for the process O þþ → γγ in the framework of a QCDmotivated Bethe-Salpeter equation (BSE). In this 4 × 4 BSE framework, the coupled Salpeter equations are first shown to decouple for the confining part of the interaction (under the heavy-quark approximation) and are analytically solved, and later the one-gluon-exchange interaction is perturbatively incorporated, leading to mass spectral equations for various quarkonia. The analytic forms of wave functions obtained are used for the calculation of the two-photon decay widths of χ c0 . Our results are in reasonable agreement with data (where available) and other models.