The aim of this work was to prepare metal soaps of epoxidized sunflower oil (ESO) and use them as thermal stabilizers for polyvinyl chloride (PVC). For that purpose, commercial sunflower oil was first epoxidized and then used to prepare (Ba, Zn, Pb, and Cd) metal soap derivatives, which were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The prepared metal soaps derivatives of ESO were used as thermal stabilizers for plasticized PVC. Discoloration, residual thermal stability at 200 degrees C, and rheological properties of PVC samples were tested. The structural modifications were investigated by UV-visible spectroscopy. The best thermal stabilization effects were observed in the presence of Pb soap of ESO. Furthermore, metal derivatives of ESO were classified according to their stabilizing effect as follows: Pb-ESO > Ba-ESO > Cd-ESO > ESO > Zn-ESO.