A catalyst composition and its use for the oxidation of ethane to ethylene and acetic acid which comprises (i) a support, and (ii) in combination with oxygen, the elements molybdenum, vanadium and niobium, optionally tungsten and a component Z, which is one or more metals of Group 14 of the Periodic Table of Elements; a, b, c, d and e represent the gram atom ratios of the elements Mo, W, Z, V and Nb respectively, such that 0