The Sm2-xSrxNiO4+delta when x = 0.4-1.0 solid solutions are synthesized by combustion followed by sintering at 1100 degrees C for 10 h, yield crystallite size in the range 73-82 nm. The single-phase Sm2_55r5NiO4-Fa are of orthorhombic and tetragonal crystal structures when x = 0.4-0.7 and x = 0.8-1.0, respectively. The maximum electronic conductivity (sigma= 0.361 S cm(-1) at 640 degrees C) for Sm(1.5)Sro(5)NiO(4+delta) is due to the extrinsic defects. The decrease in conductivity when x> 0.5 is attributed to the formation of electrically neutral clusters. The narrow particle size distribution with mean particle size 423 +/- 11 nm, of Sm1.5Sr0 5NiO4+delta is obtained by ball milling the ink/slurry at 300 revolutions per minute (rpm) for 1 h. The minimum area specific resistance (ASR) of 2.7 (3 cm(2) at 700 degrees C is obtained when x = 0.5, and is attributed to uniform superfine grains and optimum porosity of cathode. (C) 2013 Elsevier B.V. All rights reserved.