The application of a UV/photocatalyst catalyst process to convert the greenhouse air pollutants, i.e., CO2, to useful chemicals was studied. The emission of CO2 to the atmosphere was substantially found in the industrial waste gaseous streams. The photocatalysts used were Ag/TiO2 and Cu/TiO2 prepared by impregnation method. The photocatalytic reductions of CO2 were performed via three different methods. The major product via methods 1 and 2 was methanol. An addition of CuCl2 to the solution containing suspended Cu/TiO2 catalyst could produce CuCl/Cu/TiO2, which further catalytically enhanced the reduction of CO2 and CH3OH, producing CH4 and increasing its yield. The determining step for the production of methane was the additions of Na2CO3 and CuCl2 in the aqueous solution. The orders of concentrations of Na2CO3 enhancing the methane yields were 0.1 > 0.2 > 0.3 > 0.05 M Na2CO3 at 0.1 M CuCl2. Thus, the process is environmentally favorable. This is an abstract of a paper presented at the AWMA's 99th Annual Conference and Exhibition (New Orleans, LA 6/20-23/2006).