In the present work, we report on successful preparation of the Ce-Sm-O/Ru catalysts based on an organic-free modification of the sol-gel technique, since the ceria-based materials are essential as components of promoters in the many catalyst systems. A series of samples with Sm 5-15 % mol content were characterized by TEM, XRD, BET, FTIR, XPS, and ESR. Also, the catalytic properties of some Ce-Sm-O and Ce-Sm-O/Ru samples were studied. We examined powdered Ce-Sm-O samples derived from thermally treated sol-gel products - xerogels (X) and precipitates (P) of Ce-Sm hydroxides after the ammonia-promoted hydrolysis of aqueous Ce-Sm nitrates. The crystallization of amorphous materials obtained started at 600 oC resulting in cubic Ce1-xSmxO2-y (x = 0.05-0.15) solid solution. According ESR data after samples Ru-treatment, the concentration of Ce3+ centers became 100 times higher for the samples prepared by thermal treatment of xerogels. In contrast, for the samples prepared from precipitates this concentration increased only 50 times. According to XRD analysis, the sudden change of unit cell parameter for Ce1-0.1Sm0.1O2 were observed. This very sample with maximum paramagnetic centers concentration after Ru-containing solution impregnation possesses the highest catalytic activity in methane conversion reaction.