Linear 1-olefins are prepared from internal olefins by (i) reacting them in the presence of an isomerization catalyst and a tri-lower alkyl aluminum so as to cause internal olefin to isomerize to 1-olefins which displace the lower alkyl groups to form a trialkyl aluminum compound in which at least one of the alkyl groups is a linear alkyl derived from the 1-olefin, and, thereafter, (ii) reacting the trialkyl aluminum compound with a 1-olefin so as to displace the linear alkyl from the trialkyl aluminum compound, thereby forming a linear 1-olefin product which is substantially free of internal olefins.