A Pt-Ru/2 % Ce/(theta+alpha)-Al2O3 nanosized catalyst was developed for selective catalytic oxidation of CH4 to synthesis gas. The process was carried out entirely with the formation of synthesis gas at high selectivity by H-2 and CO with H-2:CO = 2.0 ratio only at Pt:Ru = 2:1 or 1:1 atomic ratio and short contact time on Pt-, Ru-, and Pt-Ru low-percentage catalysts. Samples, which were reduced by H-2 at high temperature, presented a mixture of Pt-, Ru-, and Pt-Ru nanosized particles, its alloy in the mixed catalysts. The correlation between experimental results and data of physicochemical research was established. The activity together with physicochemical properties and quantum chemical calculations for the developed low-percentage Pt-Ru catalysts was investigated.