Spinel ferrite nanoparticles have been investigated In recent years, because of its high chemical stability, saturation magnetization and coercivity. Magnetic nanoparticles of cobalt ferrites were synthesized by combustion method. Iron nitrate (Fe(NO3)3.9H2O) and cobalt nitrate (Co(NO3)2.6H2O) were used as an oxidizers and glycine (C2H5NO) was used as a fuel for this method. By changing the oxidant to fuel ratio, the adiabatic temperature of the flame and the final product could be controlled. The properties of as prepared CoFe2O4 powder were thoroughly studied to understand the structural and magnetic behavior (using powder X-ray diffraction, field-emission scanning electron microscope with electron probe micro analysis and vibrating sample magnetometer). Cobalt ferrite magnetic nanoparticles are being used for the biomedical applications. The nanoparticles were found to possess antibacterial activity against E. coli and it showed the Inhibition at a minimum concentration of 50 mg/L. © 2015 Scientific Publishers. All Rights Reserved.