Nanocrystalline and homogeneous powder mixtures of (Ni1-xCoxOy)+YSZ were obtained by combustion synthesis, and reduced in H-2 at 800 degreesC to obtain Ni1-xCox/YSZ cermets, and three layer symmetrical cells cermet/YSZ/cermet. These three layer cells were co-firing at 1450 degreesC, and then reduced to obtain porous Ni1-xCox/YSZ cermet layers with good adhesion to the electrolyte. Results obtained under OCV show that partial substitution of Ni with Co lowers the polarisation resistance, especially the main contribution which is usually most dependent on the cermets microstructure. This trend is reverted for high fractions of Co, and the polarisation resistance obtained for Co/YSZ cermets is much higher than for Ni/YSZ. The low frequency contribution of the polarisation resistance was mainly dependent on the partial pressures of H-2 and H2O, and is less dependent on the substitution of Ni with Co.