Highly dispersed ruthenium oxide clusters were synthesized on carbon nanotubes (CNTs) to form RuO2·xH2O/ CNT catalyst by a homogeneous oxidation precipitation method. Methanol oxidation was carried out on RuO2·xH2O/CNT at low temperatures for the production of diverse oxygenous products, such as methyl formate (MF) and dimethoxymethane (DMM). Unprecedented conversion rate of methanol, high up to 545 molMeOH (mol Rusurface)-1 h-1, was observed at 120 ℃. The effect of structural water in RuO2 domains on the performances of the methanol oxidation reaction was investigated by annealing them in N2 at elevated temperatures. The dehydration of RuO2 clusters decreased the oxidation ability and changed the selectivity patterns. It was suggested that the behaviors of RuO2 during the annealing process may be strongly influenced by the interaction between RuO2 and CNTs.