The performance of an anode-supported proton-conducting solid oxide fuel cell (p-SOFC) was investigated by controlling transport properties of thin electrolyte membranes. Hole conductivity in electrolyte, which induces to degrade the cell performance, was sufficiently suppressed by using lanthanum tungstate La28-xW4+xO54+3x/2V2.3x/2 (LWO) with high proton conductivity and low hole conductivity. srFe(0.95)Nb(0.05)O(3.delta) (SFN) and Ni-Ce0.9Gd0.1O2.delta (Ni-GDC10) cermet were used as the cathode and anode, respectively. GDC10 was also used as an interlayer to prevent chemical reactions between the electrolyte and electrodes. SEM images and electrochemical impedance spectroscopy showed that the boundaries between the electrolyte and electrodes were stable because GDC10 blocked chemical reactions and cation diffusion at the electrolyte-electrode interfaces. Fuel cell tests were also performed with SFN/GDC10/LWO/GDC10/Ni-GDC anode-supported single cells. The thickness of the LWO thin electrolyte was approximately 3 mu m. The OCV values were measured to be 0.88 V and 0.94 Vat 800 degrees C and 600 degrees C, respectively. Moreover, the evaluation of the leakage current indicated that thin LWO could achieve the low leakage current due to transport properties such as high proton conductivity and low hole and electron conductivities.