GdxCe1‐xO2‐δ (GDC) nanoparticles were synthesized, using continuous hydrothermal flow synthesis. By varying the synthesis conditions, particle size and morphology could be tailored. Here, particle sizes between 6 and 40 nm with polyhedral or octahedral shape could be obtained. Gd0.2Ce0.8O2‐δ nanoparticles were further processed into inks for inkjet printing. Despite the small particle size/large surface area, inks with excellent printing behavior were formulated. For proof‐of‐concept, thin GDC layers were printed on a) green NiO‐GDC substrates, and on b) presintered NiO‐YSZ substrates. While no dense layers could be obtained on the green NiO‐GDC substrates, GDC nanoparticles printed on NiO‐YSZ substrates formed a dense continuous layer after firing at 1300°C.