The room temperature mechanosynthesis of La1-xSrxGa1-yMgyO3-delta was demonstrated for a broad compositional range (x=0.05, y=0.10; x=0.20, y=0.20). This was achieved in atmospheric air with a planetary ball mill at 650 rpm in nylon containers rotating at 1300 rpm in the opposite direction. The maximum milling time was 360 min so that Zr contamination was kept below 0.25 mass%, as detected by ICP-AES. Powder X-ray diffraction revealed the formation of a perovskite phase since the early milling stages that becomes dominant in the patterns collected after milling for 360 min. The average crystallite diameter determined from XRD was ca. 30 nm, in good agreement with transmission electron microscopy observations. Ceramics with 93% of the theoretical density were obtained after sintering at 1300 degrees C. (c) 2008 Elsevier B.V. All rights reserved.