A method for isomerising n-olefins containing no more than 20 carbon atoms, wherein an olefin-containing feed is contacted with a catalyst based on alumina impregnated with 0.03-0.6 wt % of titanium and a metal from group III A in an amount of 0.05-5 % by weight of oxide. The method may then be carried out in the presence or absence of a small amount of steam.