High-density beta ''-alumina with relative density exceeding 98% was obtained by spark plasma sintering (SPS) at 1400 degrees C for 15 min. X-ray diffraction measurements and scanning electron microscopy demonstrated that the c-axis of the beta ''-alumina grains oriented along the direction of pressure application during SPS. Na volatilization was well suppressed by encapsulation in a carbon die and a short sintering time. Higher ionic conductivity was observed along the vertical direction than along the direction of pressure application owing to the alignment of the conduction plane in beta ''-alumina crystals. The highest total conductivity at 25 degrees C was 1.9 x 10(-2) S.cm(-1). (C) 2014 Elsevier B.V. All rights reserved.