Expansive clay is classified as an unstable soil. Soil stabilization of expansive clay can be achieved by means of replacement, chemical, and physical methods. This research studies the stabilization of expansive clay using chemical methods, by combining white soil from NTT with H2SO4. This study was conducted to determine the effect of adding white soil and H2SO4 to soil physical and mechanical properties and to improve expansive clay. The method used physical and mechanical testing, namely: property test, CBR, UCS, and Oedometer with variations in composition with an addition of 3%, 4%, and 5% white soil from the weight of expansive clay and 5% H2SO4 from OMC water content at 0, 7, 14, and 28 days of aging, then compared to untreated expansive clay. The results showed that physically stabilized clay became inactive, although its plasticity and expansion rate decreased. Mechanically, there was an increase in the compressive and shear strength of 43.82%, and unsoaked CBR density of 83.25% and soaked CBR of 7.4%, which is directly proportional to the aged soil. Swell potential and swell pressure decreased by 90.71% and 65.71% respectively. The optimum composition is the composition with an addition of 3% white soil and 5% H2SO4 at 28 days of aging.