In the present work a modified polymeric precursor route is applied for the preparation of La1-xSrxGa0.8Mg0.2O3-δ (x=0.1, 0.2, 0.3). Citric acid and ethylene glycol are used as chelating and complexing agents respectively and microwave heating is used for the preparation of the precursors. The sintering reactions are recorded using TG/DTG measurements, while XRD, FTIR and SEM are used for the characterization of the intermediate and final products. As it is concluded, pure La0.9Sr0.1Ga0.8Mg0.2O3 can be prepared after sintering at 1300 °C for 6h. As the doping level of Sr increases, the formation of single phase perovskite is hindered. La0.8Sr0.2Ga0.8Mg0.2O3 contains minor amounts of SrLaGa3O7, while single-phase La0.7Sr0.3Ga0.8Mg0.2O3 can not be prepared at all. In all cases, the intermediate products at lower temperatures are mainly SrLaGa3O7, SrLaGaO4, La4Ga2O7 and La carbonates.