Synthesis of copoly-(eugenol-stearyl acrylate)/Eg-co-SA was carried out through cationic copolymerization. Copolymerization was conducted using H2SO4 initiator, at room temperature (28-30 degrees C) and under nitrogen atmosphere. Structure of Eg-co-SA was identified by FTIR and H-1-NMR spectroscopy. Average molecular weight (Mv) of Eg-co-SA was measured by Ostwald Viscometer at constant temperature 28 degrees C. Morphology and thermal properties of Eg-co-SA was characterized using SEM and DSC. Analysis of EG-CO-SA structure by using FTIR showed disappear of characteristics absorption of the vinyl group (-CH=CH2) in 1638-1634 cm(-1) and 998-977 cm(-1) wave number. The success of synthesis was supported by the disappear of the H-1-NMR vinyl proton signal at 5.7-6.39 ppm and the appearance of new proton signal of single bond carbon (C-C) at 1-2.6 ppm. The increasing the weight of SA in Eg-co-SA synthesis gives changes in average molecular weight (Mv) and Degree of Polymerization (DP). The results of determining the average molecular weight of Eg-co-SA 2%, 4% and 5% were obtained 49812.10, 67709.25 and 75283.59 g/mol, respectively. Meanwhile, the degree of polymerization were 102, 139 and 154 for 2%, 4%, and 5% Eg-co-SA, respectively. Morphology of Eg-co-SA showed that increasing of SA weight resulted spongy surfaces with 0.35-10.46 mu m diameter. Thermal analysis of Eg-co-SA showed that increasing of SA weight influenced thermal stability from 399 degrees C to 386 degrees C, when the SA content increase from 2% to 4%.