Herein we report the synthesis of a magnetically separable core–shell-like Fe3O4@Boehmite-NH2-CoII NPs as an environmentally friendly heterogeneous catalyst. The as-prepared nanocatalyst was well characterized by various techniques such as FT-IR, XRD, BET, TEM, FE-SEM, EDX, TGA, H2-TPR, VSM, ICP-OES and elemental analysis and evaluated for the Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions in a green solvent (H2O). The results of characterization studies revealed the superparamagnetic behavior of the Fe3O4 NP core encapsulated by a Boehmite NP shell. Also, it was clearly found that the size of the particles was about 13–54 nm. In comparison with previously reported catalysts, Fe3O4@Boehmite-NH2-CoII NPs exhibited perfect catalytic efficiency for the Suzuki–Miyaura and Heck– Mizoroki cross-coupling reactions under mild conditions without using toxic solvents. The concerted effects between individual components of the catalyst and also its unique egg-like nanostructure led to the high catalytic performance of Fe3O4@Boehmite-NH2-CoII NPs. Also, the introduction of Co significantly lowers the cost of the catalyst. More importantly, the longevity of the nanocatalyst was studied and it was found that the magnetic nanocatalyst was stable under the reaction conditions and could be easily reused for at least seven consecutive cycles without a discernible decrease in its catalytic activity or metal leaching. Introduction Among the most fundamental reactions in organic chemistry, generating carbon–carbon bonds as a powerful synthetic tool and a major area of interest in multiple organic transformations has received a great deal of attention1,2 because the resulting coupling products are widely used for academic and industrial processes including the pharmaceutical, agrochemical, natural product and fine chemical industries.3–6 Undoubtedly, the Suzuki–Miyaura7 and Heck–Mizoroki8 crosscoupling reactions are the most beneficial and extensively used reactions for C–C bond formation due to their high efficiency and atom economy. In this context, novel transition metal complexes have been the most extensively studied catalytic systems for the Suzuki–Miyaura9 and Heck–Mizoroki10 cross-coupling

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