As the second highest countries in producing oil and gas energy, Indonesia cooperates with petroleum industry to approach the oil supply. They will put their oil refineries under the sea, which tends to get corrosion. Therefore, it is important to synthesize additive compounds having a function as corrosion inhibitor. In searching of corrosion inhibitor, imidazoline derivative was successfully synthesized by reacting tetraethylenepentamine (TEPA) and oleic acid (OA) using MAOS (Microwave Assisted Organic Synthesis) method. The optimum yield of TEPA-OA imidazoline was obtained at 9 min reaction time (82.62 %). Furthermore, the structure of TEPA-OA imidazoline had been elucidated based on UV-Vis, FTIR, and 1H-NMR spectral data. Corrosion inhibition activity of TEPA-OA imidazoline was determined towards carbon steel in 1 % NaCl solution with various concentration of TEPA-OA imidazoline using Tafel polarization method. The highest percentage of inhibition efficiency (% IE) was obtained at 500 ppm with % IE value of 86.37 %. This is the first finding of TEPA-OA imidazoline synthesis using MAOS method together with its ability to inhibit corrosion towards carbon steel.