The adsorption, decomposition, and oxidation of dimethyl ether have been investigated on Rh catalyst using alumina, magnesia, titania, and silica supports. Transmission infrared spectroscopic measurements have revealed that adsorbed ether molecules are transformed into methoxy species at 200-300 K. This process proceeds mainly on the supports. The effect of Rh is exhibited at higher temperature, above 473 K, when it catalyses the decomposition of dimethyl ether to give CO, H-2, and a small amount of CH4. The formation of strongly adsorbed species, such as CO, CHx, and C, leads to the early deactivation of the catalysts. The complete oxidation of dimethyl ether to CO2 and H2O was studied in a flow system. The reaction started above 450 K and attained almost 100% conversion at 600-630 K for all supported Rh, except Rh/MgO. There are no significant differences in the activities of other Rh samples. Taking into account the dispersities of Rh, the most effective catalyst is the alumina-, followed by titania-, silica-, and magnesia-supported Rh. Whereas at lower temperatures different hydrocarbons in minor amounts were detected in the products, above 600 K only 0.1-0.2% methane was identified. Based on the results obtained on Rh(111) under UHV conditions, it is concluded that dimethyl ether interacts with adsorbed O atoms bonded to the Rh, and the oxidation proceeds via the transient formation of methoxy species on the Rh.