Nanograined 25 mol% Sc-doped BaZrO3, BaZr0.75Sc0.25O3 (-) (delta), well-known as a proton conductor, has been successfully synthesized at low processing temperature with average grain sizes of 8.9 nm, 15.9 nm, and 68.5 nm, and the effect of grain size on the conductivity has been examined. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns for these samples suggest a simple cubic perovskite type structure. The total DC conductivity, bulk and grain boundary contributions, of BaZr0.75Sc0.25O3 (-) (delta) as-pressed at room temperature (non-sintered) is 553 x 10(-6) S/cm (8.9 nm grains) at 500 degrees C, while values of 2.68 x 10(-6) S/cm and 127 x 10(-3) S/cm are observed at 500 degrees C for those samples post-annealed at 800 C and 1250 degrees C with average grain sizes of 15.9 and 685 nm, respectively. The observed total DC conductivity for 68.5 nm grain size is almost comparable to that reported for benchmark Y-doped BaZrO3 with nanometer and micrometer grains. (C) 2014 Elsevier B.V. All rights reserved.