Starting from plausible nickel photoredox conditions we developed the decarboxylative dehydrogenation reactivity in order to obtain (Z)-enamides as pure product (Table ). To facilitate this, we employed Cbz-protected phenylalanine (1a) as model substrate. The entire optimization process can be found in the SI (Scheme S1-3 and Figure ). No dependence was observed for the employed nickel source thus the nickel(II)chloride glyme complex was used (Scheme S3). Using electron-rich and ortho-functionalized arenes like ortho-methoxy bromobenzene (X1) or 2-bromothiophene (X2) (Table and and and) both gave high yields with moderate (Z)-selectivity utilizing benchmark Ir(dF(CF3)ppy)2(dtbbpy)PF6 (Ir-1) as photocatalyst (PC). We anticipated that structural modifications on the Ir(III) complex would enable more efficient photocatalytic selectivity. Hence, we prepared derivatives with modifications on the phenylpyridine (ppy) and bipyridine (bpy) respectively (Table ) and were pleased to see that removal of the fluorine atoms on the ppy led to high yield and promising selectivity. Ir((CF3)ppy)2(dtbbpy)PF6 (Ir-3), a previously unreported photocatalyst, exhibited a higher (Z)-selectivity (4:1) combined with high yield of 76% of the β-phenyl enamide product 2a ). A detailed investigation of the physical properties of Ir-3, including UV/Vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry (CV), can be found in the SI. Strongly reducing PC like Ir(ppy)3 or Ru(bpy)3(PF6)2 performed poorly since the initial decarboxylation is unfeasible (Scheme S1) and common organic PC, like 4CzIPN, gave both low yield and selectivity (Table ), which is remarkable compared to the photochemical synthesis of (Z)-alkenes in the presence of this PC. Subsequent solvent screening revealed that lower polarity solvents like DME displayed significantly improved (Z)selectivity (18:1) combined with a high yield of 93% (Table , Entries 7-10). Functionalized thiophene X3 gave a high yield of 86% for 2a combined with exclusive (Z)-selectivity (Table , Entry 11). Similar results were obtained by using 2chlorobenzotrifluoride (X4) as another ortho-substituted additive. However, a preference for Boc-protected phenylalanine was observed (Table and). This result indicates that the steric interaction of the substrate's protecting group and the orthoeffect of the aryl halide plays an important design role for nickel photocatalytic dehydrogenation. Nonetheless, further research will shed light on the nature of sterically demanding orthosubstituents as handles for stereoselectivity in nickel catalysis. From the optimal conditions we conclude a plausible mechanism for the decarboxylative dehydrogenation reaction, which is depicted in Figure . The process initiates with the photoexcitation of Ir-3 by blue light, followed by intersystem crossing, resulting in the formation of a long-lived triplet excited state *Ir(III). Deprotonation of substrate 1a and excited state oxidation (E*red(*Ir-3 III /Ir-3 II ) = +1.24 V vs. SCE) enables rapid decarboxylation, generating the carbon-centered radical intermediate 2a'. Low-valent and in situ generated Ni(0) species I readily traps radical intermediate 2a' yielding Ni(I) species II. Oxidative addition of an aryl halide (e.g., X4) occurs, forming the key Ni(III) intermediate III. We propose that III can undergo reductive halide dissociation when reduced by Ir-3 (Ered(Ir-3 II /Ir-3 III ) = -1.40 V vs. SCE), a process previously demonstrated by Molander. Subsequently, β-H abstraction is likely to proceed from Ni(II) complex IV due to more favorable agostic interactions and its relatively high basicity, resulting in the formation of Ni(II)-H species V and dissociation of the olefin 2a. For full optimization see SI, Scheme S1-3 and Figure .