In this work, graphene oxide (GO) was reduced/modified by an eco-friendly route using L-Citrulline molecules extracted from the watermelon rind. Before and after the modification/reduction process, the rGO layers were characterized by different spectroscopy techniques. In addition, the mechanical properties of the epoxy-rGO reinforced coatings were evaluated by tensile and dynamic mechanical thermal analysis (DMTA) tests. The characterization results have demonstrated that the GO nanosheets were successfully reduced/modified by the extracted compounds. DMTA analysis showed that the values of storage modulus at glassy and rubbery regions for the neat epoxy sample incorporated with the rGO nanosheets were increased by about 39 % and 97 %, respectively. Moreover, the glass transition temperature (Tg) was increased from 76.8 °C for the neat epoxy (EP) to 84.0 °C for the EP/modified-reduced GO nanocomposite. Tensile tests showed that the values of tensile strength, maximum strain, elastic modulus, and toughness of the epoxy-based coating were respectively increased by about 142 %, 266 %, 46.7 %, and 388 % after incorporation of the rGO nanosheets compared to the EP sample.