Sr and Mg substituted LaGaO3 is a solid electrolyte for intermediate temperature solid oxide fuel cell. Phase purity of this material is a concern for the researchers for a long time. In this contribution the secondary phases that are evolved during the synthesis of Sr and Mg doped LaGaO3 are reported. For that purpose, a series of La1-xSrGa1-yMg gamma O3-delta (LSGM) was prepared by solid state synthesis route. Scanning electron microscopic photographs showed secondary phases namely La4Ga2O9, LaSrGa3O7, LaSrGaO4 along with the parent perovskite LSGM depending upon the amount of dopant. Amount of secondary phases was estimated from the peak positions of room temperature X-ray diffraction. It was observed that for a fixed amount of Mg dopant increasing the amount of Sr content also increased the amount of secondary phases whereas the reverse was found to be true when Sr content was fixed and Mg content was increased. This behaviour was attributed to the increase in solid solubility of Sr in presence of Mg. (c) 2007 Elsevier B.V. All rights reserved.