Anisotropicstructures,nanoneedles,andnanospindlesofrareearthhydroxychloride(RE(OH)2Cl)andoxychloride(REOCl)(rareearth=EuandTb)weresynthesized.Therareearthhydroxychloridenanostructureswereformedviaathermallyassistedhydrolysisoftherare-earthsesquioxidenanocrystals.Themorphologicalevolutionofthenanostructureswasstudiedusinghigh-resolutiontransmissionelec-tronmicroscopyandscanningelectronmicroscopy,whilethestructuralevolutionwasinvestigatedusingX-raydiffractiontechniques.Thethermalstabilityoftherareearthhydroxychlorideswasinvestigatedusingthermogravimetricanalysis.Therareearthoxychloridenanospin-dlesweresynthesizedviaasimpleheat-treatmentofrareearthhydroxychloridenanospindles.