La3Ni2O7±δ and La2.9Sr0.1Ni2O7±δ Ruddlesden-Popper nickelate were synthesized via citrate gel method. The electrical property of Mn and Co dopants on Ni site in these systems was investigated as possible cathode for solid oxide fuel cells. The result of X-ray diffraction shows the presence of La2NiO4 in La3Ni2-xMxO7±δ and La2.9Sr0.1Ni2-xMxO7±δ (M = Mn or Co) as M content increases from x = 0.1 for Mn and x = 0.2 for Co. With further increase of Mn dopant (x ≥ 0.4), LaMnO3 and La2O3 appear with La2NiO4. The grain size of sintered sample decreases as Mn content increases. However, it slightly decreases with increasing Co content. The TEC value increases with Co content. The DC four-point measurement shows a decrease in the conductivity as Co content increases for both La3Ni2-xCoxO7±δ and La2.9Sr0.1Ni2-xCoxO7±δ systems.