The growth of atomically thin MoS 2 films is achieved by sulfurization of molybdenum oxide precursor films grown by atomic layer deposition. The quality features of the MoS 2 films are engineered controlling the stoichiometry, morphology, and thickness of the precursors. The interface interaction between the precursor films and the substrates (SiO 2 or sapphire) plays a key role in the MoS 2 formation.