Our basic approach is to use a photoelectrochemical cell operated under simulated Mars conditions. The light source will be solar simulator with a wide spectrum of emitted light. On Mars wavelengths of light down to 190 nm reach the surface (compared to Earth where only 300 nm and above reaches the surface). The soil will be the JSC.Mars 1 stimulant which is known to contain 10% TiO2 (in partial reduced forms) and is supposed to be a good analog for the surface soils on Mars. We will consider two possible sources of H2O: first water flowing as liquid from below the surface of the soil and second water deposited as condensate on the surface of the soil. Additional two types of photocatalysts will be evaluated for methane conversion efficiencies: off shelf low cost TiO2 (P25), and doped TiO2 nanostructures (nanotubes and nanowires) for broader solar wavelength absorptions.