Ceramics of the melilite-type compound La1+xSr1-xGa3O7-delta were prepared by conventional ceramic processing. Samples prepared represented the entire homogeneity region of the phase (i.e., x = -0.15 to 0.60). Electrochemical characterization under variable temperature and atmospheric conditions in the vicinity of air entailed four-point direct-current conductivity measurements and electromotive force measurements. La1+xSr1-xGa3O7-delta samples exhibited a p-type behavior with generally increased conductivity with increased substitution of lanthanum for strontium, which reached a saturation value of similar to10(-1) S(.)cm(-1) at 950degreesC.