Materials formulated Ln(2-x-y y)Ca(x)NiO(4+delta) (with (i) x = y = 0 for Ln = La, Pr, Nd, (ii) x not equal 0 when y = 0 or y not equal 0 when x = 0 for Ln = Nd) have been prepared and characterized using various techniques with respect to their mixed ionic/electronic conducting properties. These oxides exhibit high electronic conductivity (approximate to 100 S cm(-1) at T = 700 degrees C) as well as high values of oxygen diffusion and surface exchange coefficients (D* and k, determined using SIMS analysis of the 180 isotope). The oxygen diffusion performances of Pr2NiO4+delta are the highest ones among those of the studied compounds. Interestingly, in the Nd-series they are slightly improved by the creation of Nd vacancies, while they are affected by the substitution of Nd by Ca. (c) 2005 Elsevier B.V. All rights reserved.