We began our investigation into the proposed C(sp )-H carbonylation by merging a solution of cyclohexane and di-n-butyl maleate in the presence of tetrabutylammonium decatungstate (TBADT) in acetonitrile (0.1 M) with a carbon monoxide gaseous stream. The combined segmented flow was subsequently introduced into a continuous-flow microreactor (PFA tubing, ID = 0.8 mm, 5 mL volume) irradiated with six high-intensity UV-A light sources (Chip-on-Board LED, λ = 365 nm, 144 W optical power). Further, a back-pressure regulator (BPR) was installed at the reactor outlet to maintain a constant reaction pressure (See Supporting Information for technical details). After screening various reaction parameters (see Figure and Supporting Information), we found that the targeted carbonylated product (d) could be obtained in quantitative yield in only 30 minutes residence time. Pressure was found to significantly impact selectivity, with the Giese adduct (e) as the main product at atmospheric pressure. Elevated pressure, with 34 bar as the optimal condition, reversed the selectivity towards the carbonylated product (Figure ). The residence time positively affected conversion, reaching 82% after two minutes and being complete at 15 minutes with 4 mol% catalyst loading (Figure ). With maximum light intensity (144W optical power), the photocatalyst loading can be reduced from 4 mol% to 0.25 mol% without significant loss in yield or selectivity (Figure ). However, at this low photocatalyst loading (0.25 mol%), the transformation becomes photon limited with decreased light intensity, resulting in only 59% conversion at 24W output power (Figure ). Control experiments confirmed the photocatalytic nature of the transformation, as no reaction occurred without catalyst or light. Having optimized the reaction conditions, we next investigated the scope of the photocatalytic carbonylation transformation (Figure ). First, cyclohexane was combined with CO and a variety of olefins. These olefins serve as terminal radical traps for the acyl radicals, initially formed through combination of the photocatalytically generated carbon-centered radicals with carbon monoxide. Using di-n-butyl maleate and dimethyl maleate as coupling partners resulted in the formation of the targeted unsymmetrical ketones in good isolated yields (1-2, 71-92%).