Methane activation over Al2O3-promoted sulfated zirconia (abbreviated as SZA) in comparison with SZ was studied in the temperature range 350-450 degreesC in a recirculation reactor. Over both catalysts methane was converted mainly into ethane with traces of ethylene. SZA catalyst is much more active than SZ. Based on acid site density measurements performed by H/D exchange, the higher activity of the former catalyst can be most probably assigned to a larger number of sites active for methane conversion. The obvious inhibiting effects of both CO and water on this reaction were observed. The mechanism of methane conversion over these catalysts is discussed on the basis of product distribution.