The reaction of ethane on unsupported and supported molybdenum compounds has been investigated at 773-973 K. ZSM-5 was used as support. Reaction products were analyzed using gas chromatography. Changes in the composition of catalyst samples were followed by X-ray photoelectron spectroscopy. Unsupported MoO3 is partially reduced with ethane above 800 K to give H2O and CO2. The formation of H-2, C2H4 and CH4 was also observed. Mo-free ZSM-5 exhibited relatively high activity towards dehydrogenation, hydrogenolysis and aromatization of ethane above 773 K. Deposition of MoO3 on ZSM-5 significantly enhanced the conversion of ethane and also the selectivity of benzene production. Alteration of the catalytic behaviour of MoO3/ZSM-5 in time on-stream at 773-973 It was attributed to the reaction of MoO3, to carbon deposition and to the formation of Mo2C. Unsupported Mo2C catalyzed the dehydrogenation of ethane without producing benzene. In contrast, Mo2C/ZSM-5 was found to be an effective catalyst in the aromatization of ethane. At 973 K the conversion of ethane was similar to 67% and the selectivity to benzene formation 31%.