Abstract Manganese oxide nanoparticles (MnO2 NPs) prepared by green synthesis method using Euphorbia heterophylla L. leaves extract (ELE) had been reported. Functional groups, particle size distribution, crystallinity structure, bandgap energy and morphology of MnO2 NPs were also investigated. Chemical bonding of Mn-O was confirmed by Fourier- Transform Infrared (FTIR) at 559 cm-1 wave number. The particle size of MnO2 NPs measured by Particle Size Analyzer (PSA) instrument was about 56.68 nm. Characterization using X- Ray Diffraction (XRD) indicated diffraction peaks of MnO2 NPs at 28.75o; 37.41; 42.80o; 56.74o; 59.97o; 64.95o; 72.42o and 72.63o, these peaks corresponded to the miller indices of 110; 101; 111; 211; 220; 002; 301 and 112, respectively. Bandgap energy of MnO2 NPs was 2.85 eV confirmed by UV-Vis DRS spectrophotometer. The morphology of MnO2 NPs was confirmed by Scanning Electron Microscope-Energy Dispersive X-Ray indicated the ratio of composition Mn and O atom was 34,60 and 65,40 % and Transmission Electron Microscope showed that MnO2 NPs had irregular shape