The continuous production of carbon monoxide (CO) and hydrogen (H2) by dry reforming of methane (CH4) is demonstrated isothermally using a ceramic redox membrane in absence of additional catalysts. The reactor technology realizes the continuous splitting of CO2 to CO on the inner side of a tubular membrane and the partial oxidation of CH4 with the lattice oxygen to form syngas on the outer side. La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membranes evaluated at 840-1030 °C yielded up to 1.27 μmol CO s-1 from CO2, 3.77 μmolH₂ g-1 s-1 from CH4 , and CO from CH4 at approximately the same rate as CO from CO2. We compute the free energy of the oxygen vacancy formation for La0.5Sr0.5B0.5B'0.5O3-δ (B, B'=Mn, Fe, Co, Cu) using electronic structure theory to understand how CO2 reduction limits dry reforming of methane using LSCF and to show how the CO2 conversion can be increased by using advanced redox materials such as La0.5Sr0.5MnO3-δ and La0.5Sr0.5Mn0.5Co0.5O3-δ .