In this study, the effects of various amounts of Ga3+ dopants on the densification, phase structure, microstructure and electrical conductivity of La9.5Ge6.0O26.25 ceramics are examined. The incorporation of Ga3+ ions into the La9.5Ge6.0O26.25 lattices leads to the retardation of the densification and an increase in the triclinic structure, caused by the evaporation of GeO2 and the largeness of the size difference between the Ga3+ ions and Ge4+ ions. Of the compositions studied, the La9.5Ge5.7Ga0.3O26.1 ceramic sintered at 1450°C shows an electrical conductivity of 4.02 × 10−2 Scm−1 at 800°C, which is higher than that of an 8YSZ ceramic. The calculated thermal expansion coefficient (CTE) of this ceramic of 10.4 × 10−6 K−1 appears to be compatible with those of the common adjacent materials used in solid oxide fuel cells (SOFCs). A single cell with a La9.5Ge5.7Ga0.3O26.1 electrolyte 0.51 mm in thickness is built and evaluated. The cell has R0 and RP values of 0.80 and 0.28 Ω·cm2, respectively, at 850°C. The open circuit voltage (OCV) and maximum power density (MPD) of the single cell are recorded as 1.002 V and 0.24 Wcm−2 at the measurement temperature of 850°C. Through the incorporating of a thick La9.5Ge5.7Ga0.3O26.1 layer, the cell performance of the single cell with the La9.5Ge5.7Ga0.3O26.1 electrolyte is superior to that of SOFC cells with a similar electrolyte thickness reported in the literature, thus qualifying the La9.5Ge5.7Ga0.3O26.1 ceramic as a potential electrolyte material for SOFCs.