The film formation by decomposition of tetraethoxysilane on the surface of a hot Mo wire was studied within a temperature range of 1350 to 1600 K. It is assumed that the film formation proceeds via SiO2 precursor units with liquid-like properties. They cover the Mo wire surface with a smooth layer during the first step of film buildup. When the film thickness increases an agglomeration of these precursors takes place resulting in larger particles with characteristic diameters. These units themselves form further agglomerates with a column-like morphology. In dependence on the substrate temperature, the film formation downstream of the wire results in films with residual organic groups as found by infrared and x-ray photoelectron spectroscopy.