Composite zirconomolybdate sorbents of different compositions were prepared by agglomeration of layered zirconomolybdate with a SiO₂ gel followed by impregnation of a sodium salt of bis-(2,4,4-trimethylpentyl)-phosphinic acid (Cyanex 272). Sorption properties of two composites with respect to Nd³⁺, as an actinide surrogate, and possibility of Nd₂Zr₃(MoO₄)₉ phase formation, which is similar by structure to a kosnarite mineral, by high-temperature phase conversion were studied. It was shown that the inorganic and hybrid composites trap Nd³⁺ cations from solutions with distribution coefficients of about 10⁴ mL/g and limit sorption capacities of 30 and 50 mg/g, accordingly. It was established that solid-phase crystallization of both composites with sorbed Nd³⁺ takes place at 650°C resulting in a polyphase system with the content of the target phase Nd₂Zr₃(MoO₄)₉ of about 30%.