Epoxy resin was incorporated with microcrystalline cellulose (MCC) for the production of the primer coating. Various sonication times were applied for the purpose of determining the ideal sonication period that provides the best barrier performance. The coatings were also added with various 3-Aminopropyltriethoxysilane (APTES) loadings in order to improve the mechanical and corrosion resistance properties. Fourier Transform Infrared (FTIR) Spectroscopy analysis was carried out to examine the chemical interactions and diffusion between MCC, APTES, and epoxy resin. After nine days of immersion in a 5 % sodium chloride (NaCl) solution, the ideal sonication period was found to be 30 minutes, with no corrosion occurring aggressively and no flaking or blistering appears on the coating. The anticorrosive qualities of the primer coating were eventually enhanced by the addition of MCC modified with APTES. The addition of APTES had improved the interaction between MCC and epoxy, hence achieving better compatibility and promoting a uniformly dispersed MCC throughout the Epoxy Primer Coating Filled Microcrystalline Cellulose Treated with Silane Coupling Agent on Metal Substrate Mohd Hafizie Abd Kudus1 , Zuliahani Ahmad1*, Adzrie Baharudin1,2, Munirah Onn3 , Luqman Musa4 , Azniwati Abd Aziz5 and Siti Nor Din1 1 Faculty of Applied Sciences, Universiti Teknologi MARA Cawangan Perlis, Kampus Arau, 02600 Arau, Perlis, Malaysia 2 Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia 3 Faculty of Applied Sciences, Universiti Teknologi MARA, Pasir Gudang Campus, 81750 Masai, Johor, Malaysia. 4 Advanced Polymer Group, Center of Excellence Geopolymer and Green Technology (CEGeoGTech), Universiti Malaysia Perlis, 02600 Arau, Perlis, Malaysia. 5 Bioresource, Paper & Coatings Technology Division, University of Science Malaysia, 11800, Penang, Malaysia. *Corresponding author’s E-mail: zuliahani@uitm.edu.my Received: 01 January 2023 Accepted: 10 March 2023 Online First: 17 March 2023 178 Scientific Research Journal epoxy resin matrix. The Tafel polarization results found that the addition of APTES up to 9 % gave the lowest corrosion rate at 0.004 mm/year and the highest polarization resistances at 198.69 kê­¥. This is explained by the fact that enough MCC-APTES can serve as a physical barrier and obstruct the paths used by corrosive agent to diffuse. Therefore, the MCC-Epoxy treated APTES coupling agent for metal corrosion protection has thus been successfully created