In　this　study,　alkaline　earth　metals　(Mg,　Ca,　Sr,　Ba)　doped　Nd2Ce2O7　powders　are　synthesized　by　the　gel　auto-combustion　method.　The　effects　of　alkaline　earth　metals　doped　Nd2Ce2O7　on　the　phase　structure,　chemical　stability,　microstructure,　and　electrical　properties　are　evaluated　by　the　X-ray　diffraction,　scanning　electron　microscopy,　Raman　spectroscopy　and　electrochemical　testing.　All　electrolytes　reveal　a　cubic　fluorite　structure　with　an　Fm-3m　space　group　and　remain　excellent　chemical　stability　at　different　atmospheres.　The　grain　size　and　density　of　ceramics　increase　significantly,　and　a　large　number　of　oxygen　vacancies　are　created　after　alkaline　earth　metals　incorporated　into　Nd2Ce2O7.　Generally,　the　total　conductivity　is　associated　with　the　number　of　oxygen　vacancies　and　microstructure　of　ceramics.　The　electrolyte　of　Nd1.85Mg0.15Ce2O7-δ　exhibits　the　highest　electrical　conductivity　of　0.923　×　10−2　S　cm−1　and　1.542　×　10−2　S　cm−1　in　dry　air　and　wet　5%　H2–Ar　atmosphere　at　700　°C,　respectively.　Additionally,　with　alkaline　earth　metals　doped　Nd2Ce2O7　as　electrolytes,　the　proton-conducting　single　cells　have　a　better　open　circuit　voltage　and　peak　power　density.　The　single　cell　based　on　Nd1.85Mg0.15Ce2O7-δ　electrolyte　can　reach　0.890　V　and　483　mW　cm−2　at　700　°C.　This　was　observed　to　stay　constant　without　extreme　degradation　after　short-term　testing.　©　2020　Elsevier　Ltd　and　Techna　Group　S.r.l.