Catalytic experiments on pure VPO phases and titania supported VPOx and VOx are presented for the selective oxidation of ethane to acetic acid. The effects of temperature, pressure, contact time and feed conditions are examined. The characterization of catalysts by several methods shows that different specie are present on titania according to the loading V/Ti. The correlation with catalytic results allows to propose that polyvanadates are the active specie responsible for the formation of acetic acid from ethane.