Using room temperature sputtering, we have deposited Gd0.1Ce0.9O1.95 buffer layers at the cathode/electrolyte interface of 10 cm(2) circular Solid Oxide Fuel Cells. By suitably selecting the in air annealing step, we show the possibility to control the granular properties of the Gd0.1Ce0.9O1.95 buffer layers in order to optimize the Solid Oxide Fuel Cell's electrical performances. In particular, we maximise the buffer layer grain density via an annealing process with a plateau temperature of 800 degrees C, obtaining improvements in the final Solid Oxide Fuel Cell performances with an 8% increase in the current density at 800 mV and 700 degrees C with respect to the Solid Oxide Fuel Cell annealed at 1050 degrees C, and with a 59% increase in the current density at the same voltage and temperature when compared to the standard cells with the Gadolinium Doped Ceria buffer layer produced by lithographic processes. The achieved optimization procedure clearly illustrates the potentiality of the room temperature sputtering process followed by in-air annealing step in the control of the granularity of the deposited layers. Moreover, the obtained results open the way to further studies about the industrial scalability of the used technique and to its implementation in practical large scale cell production process. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.