Ni-doped lanthanum strontium manganite (LSMN) nanopowders, La(0.7)Sr(0.3)Mn(1 x)NixO(3) (0.05 <= x <= 0.3) were synthesized at 150 degrees C for 8 h by hydrothermal reaction as a function of Ni doping concentration. The SEM analyses suggested that the calcination treatment influenced the morphology of the nanopowders. The calcined nanopowders at 1300 degrees C had agglomerated spherical structure of 44-77 nm. Meanwhile, the XRD studies revealed that the nanopowders have single crystalline phase over the range x = 0.05-0.2. In addition, the LSMN nanopowders were sintered at elevated temperatures, 1250-1350 degrees C to examine their electrical conductivity for solid oxide fuel cell (SOFC) interconnect applications under actual SOFC working condition. Their electrical conductivity gradually increased to 90.05 S/cm with Ni doping concentration x = 0.2, which were sintered at 1300 degrees C. These results suggest La0.7Sr0.3Mn0.8Ni0.2O3 displays a good performance as an optimal composition of the LSMN. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.