This paper is dedicated to the study of the relationship between the Nd2NiO4+delta powder micro-structural properties (especially particle size and crystallinity) and electrochemical properties when the oxide is used as SOFC cathode deposited on 8YSZ electrolyte coated with thin doped ceria. Nano-structured particles of Nd2NiO4+delta with controlled crystallinity, size and morphology have been synthesized using ultrasonic spray pyrolysis (USP). The series and polarization resistances measured on symmetrical half cells Nd2NiO4+delta/YDC/8YSZ/YDC/Nd2NiO4+delta are both found to be dependent on the cathode microstructure and present a similar evolution with temperature. The best results are obtained for highly crystalline cathode powders combined with a small particle size. (C) 2012 Elsevier Ltd. All rights reserved.