The thermal decomposition of velpatasvir:copovidone (1:1) was studied by simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG). The influence of the heating rate (10 oC min-1) on the TG was verified. For the determination of kinetic parameters from the TG/DTG curves, the following methods were utilized: Arrhenius equation, Horwitz–Metzger, and Coats–Redfern methods. The kinetic studies of velpatasvir copovidone showed a thermal behavior characteristic of first order according to the activation energy. The activation energy obtained was found to be about 99.93±9.09 kJ mol-1. The TGA/DTG curves demonstrate that the drug undergoes two phases of thermal decomposition. The first is due to the dehydration of copovidone. The second phase occurs at three thermal decomposition steps. The first thermal decomposition step occurred at an interval of 210.0–407.0 oC. The second thermal decomposition step occurs in the interval of 407.0–465.0 oC. The third thermal decomposition step occurs in the interval of 465.0–621.0 oC, which may be attributed to the complete thermal decomposition.