Biogenic synthesis of nanoparticle (NP) has attained wider interest in view of various advantages like simplicity, eco-friendly nature, rapidity and cost-effectiveness. In current investigation, manganese nanoparticles (MnNPs) were fabricated using Cinnamomum verum bark extracts (CVBE) using manganese(II) acetate tetrahydrate as Mn precursor. The biosynthesized MnNPs were characterized by SEM, TEM, XRD and FTIR techniques. The synthesized face centered cubic MnNPs was less than 100 nm in size, spherical, crystalline and in aggregate form. The photocatalytic activity (PCA) of MnNPs was evaluated by degrading Congo Red (CR) dye. At optimized condition of pH 7.0, 0.06 g/L MnNPs dose, 10 mg/L initial dye concentration and UV irradiation time of 60 min, the CR dye degradation was 78.5%, which indicates the photocatalytic potential of biosynthesized MnNPs. The antimicrobial activity of biosynthesized MnNPs was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. Results revealed that the potential applications of the indigenous medicinal plants for the fabrication of NPs and their subsequent application in the field of nanotechnology, which could possibly be extended for the synthesis of other metals NPs. The biosynthesized MnNPs would contain natural anti-microbial agents, which may serve for the production of potential antimicrobial agents. (C) 2018 Elsevier B.V. All rights reserved.