Li13.9Sr0.1Zn(GeO4+δ)4　(LSZG)　materials　can　exhibit　proton　conduction　by　Li+/H+　ion　exchange　in　hydrogen　atmosphere.　It　can　be　used　in　solid　oxide　fuel　cells　(SOFCs)　as　an　electrolyte.　In　this　study,　In3+　doped　LSZG　powders　are　synthesized　by　sol-gel　method.　X-ray　diffraction,　scanning　electron　microscopy,　thermal　gravimetric　analyzer,　and　electrochemical　impedance　spectroscopy　are　used　to　investigate　the　effects　of　In　doping　on　LSZG.　All　Li13.9-xInxSr0.1Zn(GeO4+δ)4　(LISZG,　0　≤　x　≤　0.3)　ceramics　exhibit　the　same　phase　with　LSZG.　The　dopant　of　In　promotes　the　sintering　activity　and　Li+/H+　ion　exchange　rate　of　LSZG.　The　optimum　doping　of　In　is　x　=　0.2.　At　600　°C,　Li13.7In0.2Sr0.1Zn(GeO4+δ)4　(0.2LISZG)　shows　a　proton　conductivity　of　0.094　S/cm　under　0.9　V　direct　current　bias　voltage.　In　addition,　the　single　cell　based　on　0.2LISZG　electrolyte　is　prepared,　and　it　has　been　demonstrated　that　the　practical　utilization　of　0.2LISZG　in　IT-SOFCs　is　feasible.　©　2022　Elsevier　Ltd　and　Techna　Group　S.r.l.