Spherical La0.8Sr0.2Ga0.8Mg0.2O2.8 precursor powders were synthesized by ultrasonic spray pyrolysis using aqueous solution of citric acid and of metal nitrate. As-prepared powders obtained by this method have a spherical morphology with a submicron size. The calcination behavior of the precursor powders of the above phases were examined in the temperature range of 1073 –1773 K in an air atmosphere. XRD, SEM, DTA-TG and BET analysis were used for determination of the composition, morphology, particle size and surface area. XRD revealed that as-prepared powders were crystallized to perovskite structure after the sintering at 1573 K for 10 h.