Long-range crystal structures, local cation/anion environments, and ionic conduction characteristics of scandia stabilized zirconia (SSZ) with different Sc compositions were investigated with the help of X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), and electrochemical impedance spectroscopy (EIS). Both Sc-45 and O-17 NMR analyses were performed. Low ionic conductivities and high activation energies observed in high-Sc samples at low temperatures were attributed to defect association and cation ordering. Published by Elsevier B.V.