 The structure revealed that all the specimens have identical space groups and index well to a cubic structure.  Crystallite size was increased with increasing the fraction of doping except for (Mg0.97Pb0.03O) due to the formation of PbO oxide.  The molecular vibration of the pure and doped specimens has the same framework.  As the incorporation of Pb 2 + ions increased, the bands got broader, and the intensities increased in the range of 800-400 cm -1 . The structural characterization was discussed in the present paper of the pure MgO nanoparticles and the doped (Mg(1-x)pbxO) nanoparticles specimens, where (0 ≤ x ≤ 0.03). The modified Pechini method was used to prepare all the specimens. From (DTA), the convenient temperature of decomposition from Mg(OH)2 to MgO was above 375°C. The structure investigation (XRD) revealed that all the specimens have identical space groups and index well to cubic structures. The obtained crystallite size by Scherrer's equation was increased with increasing the fraction of doping except for (Mg0.97Pb0.03O) due to the formation of PbO oxide. The molecular vibration by FTIR demonstrated that all the pure and doped specimens have the same framework. As the incorporation of Pb2+ ions increases, the bands get broader, and the intensities increase in the ranging 800-400 cm-1 due to vibrations of O-Mg and O-Pb bands, respectively.