The formation mechanism of columnar structures is analysed by the investigation of texture and morphology of oxygen-contaminated aluminium thin films. The responsible mechanism for the structure evolution is the oxygen-induced competitive growth that results in an inhomogeneous structure of small-grained and V-shaped columnar morphology and in the appearance of (311) and (100) texture, The increase in the oxygen incorporation induces competitive growth of initially formed randomly oriented crystals due to the anisotropy of the chemical interaction of oxygen with the different crystallographic faces. At high-oxygen contamination level, the growth morphology of films is changing to a lower zone of the structure zone models,