A lanthanum oxide carbide of the general formula La2O2C2 has been prepared in a carbon monoxide atmosphere by a variety of techniques. Preparations which were zone refined by slow passage of an arc over the sample yielded a crystalline phase which was monophasic both by X-ray diffraction and micrographic analysis. Vapor phase chromatographic analysis indicates the principal species of the acid hydrolysis product of this phase is acetylene. From a carbon monoxide equilibration study of the reaction, La2O3(s) + 3 C(s) = La2O2C2(s) + CO(g) effected in a constant volume system the following data were obtained: ΔH°298 = 82.2±1.9 kcal/gfw ΔS°298 = 36.7±3.6 eu. Combination of these values with the appropriate thermodynamic data yields an elthalpy of formation of -320.0±2.0 kcal/gfw for La2O2C2. A third law enthalpy is also calculated.