BACKGROUND: Natural polymers have gained increased attention in reducing the dependence on petroleum-based materials. Chicken feather proteins are an abundant industrial by-product suitable for the fabrication of sustainable thermoplastics. However, protein-based plastics generally exhibit poor physical and thermal properties which limit their application. In this research, the fabrication of feather keratin based nano-reinforced biocomposites by the addition of graphite oxide (GO) in a reactive extrusion system were investigated. The effects of GO carbon/oxygen ratio (C/O, 2.48, 2.07, and 1.55) and concentration (0.5-2%) of the selected GO on the conformational, physical and thermal properties of thermoplastic films were investigated. RESULTS: Chicken feather-GO nanocomposites were successfully prepared at 150 degrees C in the reactive extrusion system. Tensile strength and Young modulus of chicken feather plastic films were significantly increased without affecting their elongation using low GO concentrations (0.5 to 1.5% w/w of protein). Our results suggest that higher content of hydroxyl groups and increased graphene interlayer space in GO facilitated interactions with feather keratin and plasticizers. CONCLUSIONS: Graphite oxide proved to be an inexpensive alternative to graphene for the reinforcement of protein based composites. Extrusion provided a cost-effective and environment-friendlymethod for the processing of sustainable composites. (C) 2017 Society of Chemical Industry