Sodium ion conducting electrolytes are important for a variety of applications from batteries for energy storage to chemical sensors for emission monitoring or process control. These applications span a range of temperatures, sizes and design constraints, so a variety of different electrolytes are needed. In this paper, the properties of ceramic and polymer electrolytes will be reviewed. The focus will be on discussion of the ionic conductivities and providing a comparison of the results reported in the literature for different electrolyte materials. (C) 2012 Elsevier B.V. All rights reserved.