Imidazoline is an organic compound that widely used as a corrosion inhibitor. Based on its structure, imidazoline is a heterocyclic compound having a pendant group and hydrocarbon chain which important for its activity as corrosion inhibitor. This research was conducted to modify the imidazoline structure to increase its activity in inhibiting corrosion towards carbon steel. In this research, ester-imidazoline from aminoethylethanolamine (AEEA) and oleic acid (OA) was successfully synthesized with an equivalent ratio of 1:2 (mole/mole) in xylene solvent with various reaction times using MAOS (Microwave Assisted Organic Synthesis) method. The optimum yield was obtained at 9 min reached 87.53 % yield. Ester-imidazoline was analyzed using thin layer chromatography (TLC) and elucidated using FTIR, UV-Vis, and 1H-NMR spectral data. Furthermore, the ability of ester-imidazoline to inhibit corrosion was measured towards carbon steel in 1% NaCl with various concentrations using Tafel polarization method to afford the inhibition efficiency (% IE). The highest % IE was yielded in 100 ppm with % IE value of 51.26 %. This study reported the first modification of imidazoline to yield ester-imidazoline using MAOS method along with its anticorrosion activity.