Solid electrolyte materials Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (NASICON, R-3c) were synthesized via novel acetate routes A (simple precipitate), A1 (spray-dried precipitate) and B (sol–gel synthesis) and their properties are compared. Spray-dried spherical granules show characteristic features as a result of their particular microstructure. Temperature dependent DC measurements provide an informative basis to discuss two different grain boundary ionic conduction mechanisms in these spray-dried granules.