An amorphous SiO2 substrate was co-implanted with 175 keV Mo+ and 74 keV S+ ions at doses of 4.97 × 1016 and 1.02 × 1017 cm−2, respectively. Energies of the Mo+ and S+ ions were chosen to obtain nearly overlapping depth profiles. Transmission electron microscopy and Rutherford backscattering techniques were used to characterize the ion-implanted materials. The formation of a MoS2 phase was observed in the as-implanted condition. Annealing of the as-implanted material was performed in an oxygen-free atmosphere as well as in air. The MoS2 phase remained stable at 700 °C for 8 h in an oxygen-free atmosphere whereas it starts oxidizing in air at 600 °C for 2 h. Results are discussed in terms of the available data on the oxidation of MoS2 coatings.