Disclosed is a homogeneous catalyst having a single phase of Perovskite oxide, wherein at least one doping element is substituted at site A, site B or sites A and B in ABO3 Perovskite type oxide so that the wettability with a liquid molten carbonate electrolyte may be decreased. The catalyst may have high catalytic activity, inhibit catalyst poisoning caused by creepage and evaporation of a liquid molten carbonate electrolyte, maintain high reaction activity for a long time, provide high methane conversion, and allow production of synthetic gas having a high proportion of hydrogen.