This paper aims to investigate the magnetic and electrical properties of magnetic tunnel junctions with MgO barriers. The magnetoresistance of the junction is measured at 0.4 V. Results show a magnetoresistance of almost the same values at varying radical oxidation time and Mg thickness. It is also confirmed in this study that the MgO formed by radical oxidation of Mg shows high magnetoresistance as compared to the conventional RF deposited MgO barriers.