Effective methods for rare earth separation remain an important challenge that could benefit from new approaches. In this study, we demonstrate that for La/Ce separation, an in situ electrochemical Redox process in combination with Extraction and Stripping would provide very efficient separation of these elements in a single extraction step (CeRES). By combining in situ electrochemical oxidation and simultaneous solvent extraction with a stripping process involving electrochemical reduction, separation of Ce ³⁺from La ³⁺is achieved. Here, Ce ³⁺is electrochemically oxidized to Ce ⁴⁺and removed from the aqueous phase by solvent extraction with 100 mM D2EHPA in n-octane. To recover Ce ⁴⁺from the loaded organic phase, in situ electrochemical reduction of Ce ⁴⁺to Ce ³⁺is employed. Thus, extraction and stripping by the redox state change triggered only by electrochemistry are achieved for the first time by using a shared organic phase. The approach was verified in a rapid prototype cell using the additive manufacturing technique, which enables a high Ce extraction of 85% and its recovery with nearly 100% purity in a single extraction step without the use of additional reagents.