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Abstract Quinoa husk (QH) is often discarded without being utilized. This study investigates an alternative route for this agro-waste resource as a raw material in the preparation of bioplastic composites. The effect of QH on the mechanical and thermal properties of thermoplastic poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends was evaluated. The composites were prepared by melting compounding. The content of quinoa husk in composite materials varied from 0-30 wt%. The results demonstrated that addition of quinoa husk in PLA/PBAT blend induced slight increase in crystalline phase of PLA, which was evidenced by FTIR and DSC analysis. However, it reduced the mechanical and thermal properties of materials. The 30 wt% load of quinoa husk in formulation led to decreased tensile strength (by 45.5%), elongation at break (by 85.8%), thermal stability (by 23.5%) and flexural strength (by 36%) of final biocomposite material, when compared to the control biopolymer blend. Although addition of quinoa husk in bioplastic material did not improve mechanical properties, load of 20 wt% QH in PLA/PBAT still provided satisfied tensile strength of 19 MPa and flexural strength of 27 MPa, showing that quinoa husk can add value to lignocellulosic by-product/agro waste, particularly decreasing the cost and increasing the sustainability of bioplastic materials for use in the agriculture industry.