New amorphous molybdenum oxysulfide thin films were obtained by r.f. sputtering. They can be used as positive electrodes in microbatteries. These films. as a first step, were mainly characterized by TEM. Some randomly oriented ordered domains were found; they were identified by electron diffraction as 2H-MoS2-like phase. After the films are annealed, the same kind of domain is visible; in addition, large single crystals identified as MoO2 are present. XRD confirms the presence of both compounds. The position of the main diffraction lines of the 2H-MoS2-like phase shifts when the composition of the thin films changes, indicating a partial substitution of sulfur by oxygen. An explanation is given, based on geometrical and electronic considerations.