In this study, effect of mechanical activation in planetary ball mill and disc mill, on carbothermic reduction of celestite ore with coke was investigated. Celestite ore (96% SrSO4) from Sivas district was blended with excess metallurgical coke and mechanically activated for 1, 5, 15 and 45 min. Mechanically activated blends were analyzed by Particle Size Analyzer, Thermal Gravimetric Analyzer (TGA), Differential Scanning Calorimetric Analyzer (DSC), and X-Ray Diffractometer (XRD). The finest particles were obtained at 45 min disc milling, of which d50 was 1.30 µm. TGA and DSC analyses showed that the reaction temperature was decreasing from 973°C to 892°C, by 1 min disc milling and 45 min planetary ball milling, respectively. XRD peaks broadened and peak intensities decreased by extending the mechanical activation time in both type of milling processes. All of the mechanically activated powders were roasted at 900, 1000, and 1100°C. According to XRD analyses; it is possible to see some peaks of strontium sulphide (SrS) after roasting at 900 and 1000°C, however, at 1100°C carbide formation is obtained