Mixed oxide-ion and electron conducting ceramic material La₂NiO_4+d (LNO) have been reported to exhibit impressive oxide ion and p-type electronic conductivity, and high catalytic activity which makes them an excellent component of some electrochemical devices such as fuel cell cathode, oxygen permeation membrane and sensors. The structure of hyper-stoichiometric LNO is consists of alternating LaNiO₃ perovskite and LaO rock salt layers. The oxygen excess in LNO is associated with the incorporation of interstitial oxygen into the rock salt layers and holes are simultaneously created in the perovskite layers to maintain the charge neutrality of the system. Given the oxygen activity difference across an oxide, its electrochemistry is determined by its ambipolar conductivity or the product of its oxide ionic conductivity and electronic transference number or vice versa. The partial ionic and electronic conductivities which govern the mass transport in an electric field are thus the most important properties of an electrochemical device material to characterize and understand. However, there are very few reports on the study of transport properties of mixed conducting oxide material. In this work we have analyzed the partial conductivity of La₂Ni_0.95Al_0.05O_4.025+d in relation with the thermoelectric power and calculate diffusion coefficient and surface exchange coefficient in order to analyze the oxygen exchange kinetics of La₂Ni_0.95Al_0.05O_4.025+d.