The solid-state characteristics of dextran complexes precipitated from aqueous solutions with three different light-lanthanoid cations (La3+, Ce3+, and Nd3+) were investigated by spectroscopic and thermal methods. Spectroscopic characterization was realized by the comparative interpretation of the FTIR spectra, and the complexes were found to involve both ligating water and dextran through its O(2) and O(3) atoms. Remarkable spectral changes were noted, particularly with La3+, which parallels the previous solution studies. The order of La3+ > Ce3+ > Nd3+ was determined to display the tendency of the Ln(3+) ion in favor of dextran throughout the competition between water and dextran. The thermal stabilities of the complexes were examined by thermogravimetry (TG), differential TG, and DSC methods. The decomposition steps and temperatures were assigned with respect to the lanthanoid ions used. The TG and DSC results indicated that the complexes are less stable thermally than dextran itself with increasing thermal stabilities in the order of La3+ < Ce3+ < Nd3+ in their anhydrous states.