The applicability of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid) (DOTP) for intra-lanthanide (Ln) separation was investigated through two approaches: the synthesis of inorganic-organic hybrid sorbents and selective precipitation in an aqueous solution. Hybrid sorbents combining zirconium oxide and DOTP were fabricated through post-synthetic grafting and hydrothermal synthesis. The successful syntheses were verified by FTIR and ³¹P magic-angle spinning (MAS) NMR spectroscopies. All the hybrid sorbents showed a lanthanide uptake of approximately 10-20 μmol/g at pH 3 and displayed only moderate selectivity, with the highest separation factor (SF) of about 10 for Lu³⁺ over La³⁺. In contrast, the selective precipitation of lanthanides by DOTP in an aqueous solution was successful in the presence of Cu²⁺. When a Cu-DOTP complex was introduced into a La/Lu equimolar solution, lanthanide ions were selectively precipitated with an SF of approximately 30-190. When the initial stoichiometry was set to Ln:Cu-DOTP = 8:1, roughly 95 % of the lanthanides in the precipitate were Lu³⁺, regardless of the pH ranging from 3 to 5. This precipitation process demonstrated selectivity even for adjacent lanthanide pairs. The selectivity is assumed to be a result of structural variations in the precipitates of Ln-Cu-DOTP, which is supported by the characterization results obtained from Xray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV-Vis spectroscopy. The findings presented in this study indicate that DOTP has the potential for use in the selective extraction of lanthanides, which may offer promising advancements in intra-lanthanide separation.