Polyetherimide-Graphene (PEI/G) composites were prepared and investigated as anti-corrosion coatings on Stainless Steel 304 (SS304) substrates. A small load of graphene was incorporated in the polymeric matrix using in situ polymerization approach and the coating was cured under vacuum by several steps thermal imidization. The morphology was examined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The study demonstrates that advanced corrosion inhibition of SS304 can be achieved by coating the metal with PEI and this inhibition can be further enhanced by incorporating graphene. This conclusion was supported by the collected results from electrochemical techniques such as Tafel polarization and electrochemical impedance spectroscopy (EIS). In addition to corrosion protection, the interface adhesion between the protected substrate and the protective coating was evaluated according to ASTM standards.