Green synthesis of Nanoparticles gained much momentum because of its therapeutic uses and also has environmental benefits over traditional chemical methods. The present study describes the costeffective eco-friendly synthesis of Zinc oxide nanoparticles from Acorus Calamus aqueous extract widely used as medicine in the traditional ayurvedic system of Kerala. The SEM analysis shows the synthesized ZnONPs are spherical and hexagonal wurtzite in structure and it was confirmed by the XRD data. The FTIR spectra revealed the role of Chemical moieties in the formation and stabilization of ZnONPs. The Acorus Calamus ZnONPs shows promising antioxidant activity and it shed light upon the role of phenolic compounds transferred from the plant during synthesis. The in vivo application of ZnONPs was very limited in the literature. The Acorus calamus ZnONPs may expect to serve as an alternative antioxidant supplement against disorders caused by oxidative stress and infections. (c) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.