Strontium substituted lanthanum manganites La_1–xSr_xMnO₃ (x=0, 0.1, 0.16, 0.2 and 0.3) have been prepared by a solution combustion process using lanthanum nitrate, strontium nitrate and manganese nitrate as oxidizers and oxalyl dihydrazide as fuel at 300 °C in a pre-heated muffle furnace. As-formed lanthanum manganites are X-ray crystalline showing cubic symmetry. The cubic LaMnO₃ with 36% Mn⁴⁺ changes to a rhombohedral phase (Mn⁴⁺=28%) on calcination at 1000 °C. The surface area and average agglomerated particle size of the as-formed manganites are in the range 12–19 m² g^–1 and 5.4–8.0 µm, respectively. Sintering, thermal expansion and dc electrical conductivity measurements of La(Sr)MnO₃ have been carried out. Strontium substituted lanthanum manganites achieve >80% theoretical density after sintering at 1350 °C for 4 h and the percentage theoretical density decreases with increasing strontium content. The thermal expansion coefficient of La(Sr)MnO₃ increases with increasing Sr²⁺ content and La_0.84Sr_0.16MnO₃ shows a highest conductivity value of 202 S cm^–1 at 900 °C in air.