The growth of vacuum-sublimed tetracene thin films on silicon dioxide has been investigated from the early stages of the process. The effects of deposition flux and substrate silanization on film morphology and electrical properties have been explored. Tetracene shows an island growth, resulting in films with a granular structure. Both an increase in the deposition flux and the substrate silanization determine a decrease of the grain size and an improvement of the connectivity of the film in direct contact with the substrate. The hole mobility in field-effect transistors based on tetracene thin films, which also generate electroluminescence, increases with the deposition flux and values as high as 0.15 cm2 V–1 s–1 are obtained.