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 MoO 3 is partially reduced with ethane above 800 K to give H 2 O and CO 2 . The formation of H 2 , C 2 H 4 and CH 4 was also observed. Mo-free ZSM-5 exhibited relatively high activity towards dehydrogenation, hydrogenolysis and aromatization of ethane above 773 K. Deposition of MoO 3 on ZSM-5 significantly enhanced the conversion of ethane and also the selectivity of benzene production. Alteration of the catalytic behaviour of MoO 3 /ZSM-5 in time on-stream at 773–973 K was attributed to the reaction of MoO 3 , to carbon deposition and to the formation of Mo 2 C. Unsupported Mo 2 C catalyzed the dehydrogenation of ethane without producing benzene. In contrast, Mo 2 C/ZSM-5 was found to be an effective catalyst in the aromatization of ethane. At 973 K the conversion of ethane was ∼67% and the selectivity to benzene formation 31%.