Ab initio self-consistent field (SCF), Moller-Plesset second-order perturbation theory (MP2), complete active space multiconfiguration self-consistent field (CASSCF) followed by multireference singles and doubles configuration interaction (MRSDCI), and relativistic configuration interaction (RCI) studies to include the spin-orbit effects were carried out on LaC2. The enthalpy of the La(g) + 2C(graph) = LaC2(g) reaction as well as the atomization and dissociation (La-C-2) energies were computed for the theoretically determined structure. The experimental Gibbs energy functions (GEF) were corrected by using the symmetrical C-2v structure instead of the assumed (incorrect) unsymmetrical linear geometry. The corrected experimental enthalpies thus obtained agree with the theoretically computed results.