With this apparatus in hand, we embarked on its validation, conducting a series of transformations, encompassing electrochemical, photochemical, and electrophotocatalytic processes (Scheme 2A). In verifying the reactor for electrochemistry, we opted for the synthesis of vinyl sulfones from cinnamic acids and sodium sulfinates, as detailed by Zha, Wang, and coworkers . Notably, pushing a mixture of cinnamic acid and sodium phenylsulfinate through the reactor yielded the desired product at 90%, with a residence time of 4.4 minutes and a total charge of 3 F. This outcome mirrors the results presented in the original paper, underscoring the feasibility of conducting electrochemical-only reactions with our new reactor concept. In a parallel vein, the f-EPC reactor was explored under photochemical-only conditions by executing a photocatalytic Giese-type radical hydroalkylation (18). When a mixture of dimethyl maleate and cyclohexane was flowed through the reactor, a good performance was observed, achieving a 60% 1 H-NMR yield of the anticipated product within a 10-minute residence time (further information are reported in the Supporting Information in Section S2) . While the preliminary results positively showcased the ability of the reactor to handle electrochemical and photochemical processes, achieving a successful outcome in electrophotocatalytic transformations presented a unique challenge, necessitating meticulous tuning of the kinetics within electron-and photon-driven elementary steps to increase efficiency. Inspired by our previous work (14d), initial investigations commenced by studying Table . Optimization of reaction conditions and control experiments for the electrophotocatalytic C(sp 3 )-H heteroarylation in flow. [a] Entry Variation from conditions Yield [b] 1 Yields determined by 1 H NMR spectroscopy using CH2Br2 as external standard. Yield of the isolated product is given in parenthesis.