Recently, the authors have reported the compatibility of a nonproton-conducting oxide, yttria-stabilized zirconia (YSZ), for the ceramic matrix phase in the composite anode supports of thin-film protonic ceramic fuel cells (PCFCs). In the previous work, it was identified that the NiO-YSZ anode support not only reduces the fabrication temperatures but also eases to produce the thin-film elements for PCFCs over them, providing an easily-sintered and flat substrate. The current study shows the effect of the NiO-YSZ supports on the performance of thin-film PCFCs when grain sizes of the supports increase. From comparison with the previous study, it was found that OCVs increased slightly but the power outputs dropped to about half at the operating temperature regime of 450-650°C. It represents that the non-proton-conducting support is not directly involved in the fuel cell reaction of PCFCs, but the electrochemical performance is closely related the preparation of the anode support. The details are discussed in this manuscript.