Lanthanum oxide-based catalysts are active in the elimination of HCl from C2H5Cl, 1,2-C2H4Cl2 and 1,1,2-C2H3Cl3 leading to the formation of their respective chlorinated ethenes. An oxygen-rich catalytic surface may form CO, CO2 and C2HCl as side products, whereas with chlorine-rich catalytic surfaces a stable product distribution is achieved with 100% selectivity towards the formation of ethenes, such as the valuable C2H3Cl intermediate.