In this study, the thermal degradation, dynamic mechanical and morphological properties of polyvinyl chloride (PVC) stabilized with tannin-based epoxy resin and with Ca/Zn-based thermal stabilizers were studied. The efficiency of tannin epoxy resin as thermal stabilizer and additive for PVC was explored in this work using thermogravimetric analysis, dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM) techniques. The obtained TG results reveal that the tannin-based epoxy resin as well as Ca/Zn-based thermal stabilizer has a significant effect on the thermal stability of PVC. The viscoelastic properties of PVC with and without tannin epoxy resin were evaluated by dynamic mechanical thermal analysis technique (DMTA). It was observed that the tannin derivative has an improvement effect on the viscoelastic properties of PVC. The glass transition temperature of PVC/tannin epoxy resin occurs at about 90-93 A degrees C and it is close to that of PVC formulated with Ca/Zn-based commercial thermal stabilizer and without using a plasticizer. DMTA properties show that PVC incorporated with tannin epoxy resin have relatively more recognized flowing stage which occurs smoothly at 160 A degrees C. Other analytical techniques such as SEM and energy dispersive X-ray spectroscopy are employed on PVC morphological properties. Experimental results confirm that the tannin epoxy increase thermal stability of PVC which exhibits smooth and homogenous surface properties compared to the commercial thermal stabilizer.