The complex formation of protactinium(V) with ethylenediaminetetraacetic acid (EDTA) was studied at tracer concentration ([233Pa(V)] ~ 10−12 mol·L−1) by the solvent extraction technique at 25 °C, I = 1.0, and different acidities ([HClO4] = 1.0, 0.1, 0.025 mol·L−1). The aqueous phase employed for the solvent extraction experiment was Pa(V)/H2O/HClO4/NaClO4/EDTA at 25 °C for I = 1.0, and the organic phase was xylene with a chelating agent, thenoyltrifluoroacetone (TTA). A 1:1 complex between Pa(V) and EDTA was identified using solvent extraction experiments. The obtained complex formation constant of PaO(OH)(EDTA)2− was large, and the Pa(V)–EDTA complex was stable.