Layered sodium-ion cathode material P2-Na0.85Li0.17Ni0.21Mn0.64O2 was investigated using operando XAS to characterize structural changes occurring in the material during electrochemical sodiation/desodiation. Based on XANES data, the primary mode of charge compensation in this material is due to Ni2-3/4+ redox activity, while the Mn remains in the +4 oxidation state, thereby providing stability to this material during extended cycling. Investigation of the initial state of the compound by high resolution synchrotron XRD and Li-6 MAS NMR revealed a significant amount of structural disorder due to integration of a small amount of monoclinic layered Li phase within the overall hexagonal layered Na-structure, which manifests as Li-induced stacking faults. High quality EXAFS data could be obtained using our cell construction and revealed the local structural evolution around the redox active Ni centers. (C) 2014 The Electrochemical Society. All rights reserved.