In the present work we report the synthesis of La1−xMgxMnO3 (with x = 0.10, 0.25, and 0.50) polycrystalline samples based on LaMnO3 (LMO) antiferromagnetic with low Neel temperature and insulating behavior. Structure was analyzed by Rietveld fitting of XRD patterns at room temperature by FullProf software, these show that La1−xMgxMnO3 (x = 0.10, 0.25, 0.50) samples crystallize in the space group R-3c. Magnetic and electrical measurements exhibits ferromagnetic and semiconductor like behavior. A decreases of TC is observed when x doping value increases.