Magnetic MnFe₂O₄ nanoparticles were prepared via the rapid combustion process, the morphology, chemical composition, microstructure and magnetic property of them were investigated by SEM, EDX, XRD, TEM, SAED and VSM. The as-prepared magnetic MnFe₂O₄ nanoparticles calcined at 400 °C for 2 h with absolute alcohol of 50 mL were characterized with the average nanoparticle size of about 55 nm and the specific magnetization of 64.9 Am²/kg. The adsorption kinetics and adsorption isotherms of Congo red (CR) from aqueous solutions onto MnFe₂O₄ nanoparticles were investigated by UV spectroscopy at room temperature; the adsorption kinetics data were in good agreement with the pseudo-second-order kinetic model in the initial CR concentrations of 150-300 mg/L. By comparison of the Langmuir, Freundlich and Temkin models for adsorption isotherms of CR, the Temkin model (correlation coefficient R² ═ 0.9983) could be used to evaluate the adsorption isotherm of CR onto the magnetic MnFe₂O₄ nanoparticles at room temperature, which suggested that the adsorption of CR onto the magnetic MnFe₂O₄ nanoparticles was a hybrid of monolayer and multilayer absorbing mechanism.