In this work, La₂NiO_4+δ-xCe_0.55La_0.45O_2-δ (denoted as LNO-xLDC) with various LDC contents (x = 0, 10, 20, 30, and 40 wt%) were prepared and evaluated as bifunctional oxygen electrodes for reversible solid oxide cells (RSOCs). Compared with the pure LNO, the optimum composition of LNO-30LDC exhibited the lowest polarization resistance (R_p) of 0.53 and 0.12 Ω·cm² in air at 650 and 750 ℃, respectively. The enhanced electrochemical performance of LNO-30LDC oxygen electrode was mainly attributed to the extended triple phase boundary and more oxygen ionic transfer channels. The hydrogen electrode supported single cell with LNO-30LDC oxygen electrode displayed peak power densities of 276, 401, and 521 mW·cm^-2 at 700, 750, and 800 ℃, respectively. Moreover, the electrolysis current density of the single cell demonstrated 526.39 mA·cm^-2 under 1.5 V at 800 ℃, and the corresponding hydrogen production rate was 220.03 mL·cm^-2·h^-1. The encouraging results indicated that LNO-30LDC was a promising bifunctional oxygen electrode material for RSOCs.