This study examines and evaluates the chemical modification of bitumen using a chemical agent called thiourea dioxide. A substance that has long been used as a reducing agent. Thermal weighing analysis indicated the formation of new chemical compounds obtained through the reactions between the thermal decomposition products of tahr dioxide and polar bitumen molecules (chemical modification of bitumen with thiourea dioxide). Due to these reactions, which continued even after 60 days, the permanent deformation resistance of bitumen at high temperature is improved, which is shown by a significant increase in elastic properties and viscosity. On the other hand, the increase in purity dioxide causes changes in the colloidal nature of bitumen, which in turn leads to the improvement of flexibility at low working temperatures, and hence increases its resistance to thermal cracking under loading. In fact, dynamic bending tests showed a significant reduction in the glass transition temperature value of the binder, which was confirmed by differential growth calorimetry. As a result, Tahr dioxide can be considered as a suitable modification agent that increases the working temperature range so that at this temperature, bitumen exhibits a satisfactory performance (chemical modification of bitumen with di Oxidithiourea).