A scalable method of oxalate co-precipitation was used to prepare magnesium oxide (MgO) nanoparticles. The precipitant used was oxalic acid and the source of soluble magnesium was magnesium sulfate.  Highly crystalline MgO nanoparticles prepared by calcining at 700  were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Atomic Force Microcopy Analysis (AFM). The (MgO) nanoparticles were employed to investigate the adsorption performance of Methyl Violet (MV) dye from aqueous solutions under different conditions, i.e., contact time, pH, dye concentration and temperature.  Maximum adsorption (96%) was obtained at time (60 min.), pH 6, at (20  ) and adsorbent dosage (0.05 g/L). It was found that the effect of temperature is inversely proportional to the percentage of dye removal in the studied range (20-50 ). Pseudo-second-order (R²=0.9968) and Langmuir models (R²=0.9931) described excellent fits in kinetic and isotherm experiments, respectively, indicating monolayer coverage and chemisorption. The greater adsorption capability of MgO was verified in comparison to equivalent adsorbents (qmax=83.1 mg/g).