<p>The objective of this study is to examine the influence of oxygen potentials (air, 50 pct Ar-50 pct O₂ gas mixture, and pure O₂) on the oxidation roasting of MoS₂ concentrate in a rotary kiln operating at 600 °C. In condition of air gas, there was a steady decrease in S content with an increase in reaction time. The 50 pct Ar-50 pct O₂ gas mixture exhibited accelerated rates of S removal. The most rapid decline in S content was observed with the use of pure O₂ gas, reaching negligible levels (&lt;1 pct) within 30 min, indicating highly efficient oxidation. Qualitative and quantitative X-ray diffraction analyses identified MoS₂ and MoO₂, with a conversion rate of approximately 45 pct after 30 min in air. After 60 min, some MoO₂ (~10 pct) remained, while 80 pct of MoO₃ was formed. Higher O₂ potentials accelerated oxidation, forming MoO₃ within 5 min under 50 pct Ar-50 pct O₂ and pure O₂. After 30–60 min, most MoO₃ was formed (90–95 pct) with some intermediate Mo oxide phases (Mo₄O₁₁ and Mo₉O₂₆). The formation of the agglomerated powder is negligible under both air and 50 pct Ar-50 pct O₂ mixture conditions in entire reaction time. However, the agglomeration increased to approximately 20–30 pct as the reaction time increased to 60 min in the pure O₂ atmosphere. An assessment of the oxidation roasting trajectory of MoS₂ and its phase stability was conducted through Mo-O-S predominance and Mo-S phase diagrams. The conversion rate differed depending on the O₂ potential, indicating the importance of controlling it during oxidation roasting. The acceleration of MoS₂ oxidation by higher oxygen potential enables the rapid formation of MoO₃. However, Mo₄O₁₁ and Mo₉O₂₆ can also be formed, potentially reducing productivity. Consequently, appropriate O₂ potential control is necessary to attain optimal MoO₃ productivity by minimizing Mo loss during MoS₂ oxidation roasting.</p>