A new type of oxide-salt composite electrolyte, gadolinium-doped ceria (GDC)-LiCl-SrCl 2 , was developed and demonstrated its promising use for intermediate temperature (400-700 o C) fuel cells (ITFCs). The dc electrical conductivity of this composite electrolyte (0.09-0.13Scm - 1 at 500-650 o C) was 3-10 times higher than that of the pure GDC electrolyte, indicating remarkable proton or oxygen ion conduction existing in the LiCl-SrCl 2 chloride salts or at the interface between GDC and the chloride salts. Using this composite electrolyte, peak power densities of 260 and 510mWcm - 2 , with current densities of 650 and 1250mAcm - 2 were achieved at 550 and 625 o C, respectively. This makes the new material a good candidate electrolyte for future low-cost ITFCs.