Dispersive soils, due to their high erodibility and cation exchange sensitivity, pose significant challenges in geotechnical applications. This study investigates the engineering behavior of such soils under a wide range of thermal regimes (25-900 degrees C), focusing on their mechanical, hydraulic, and physicochemical properties. Unlike previous studies that emphasized microstructure alone, this research integrates a broad range of analytical methodsmineralogical (XRD, SEM), chemical (CEC, SSA, carbonate content), and geotechnical (Atterberg limits, unconfined compressive strength, permeability, TGA) to capture a comprehensive understanding of thermal stabilization effects. Results reveal that thermal treatment significantly enhances soil performance: at 300 degrees C, dispersion decreased by 65% due to complete free water removal; at 500 degrees C, dehydroxylation induced structural rearrangement and mineral breakdown, improving both strength and permeability. At 700 degrees C and beyond, the formation of cementitious phases such as gehlenite and anorthite transforms the soil into a dense, non-dispersive medium, increasing UCS by 36.5 times and permeability by 12,000 times. These findings emphasize the effectiveness of high-temperature treatment as a sustainable and technically sound approach for stabilizing dispersive soils in geotechnical and environmental applications, including landfill liners, geothermal barriers, and contaminant containment zones.