In this work, the magnetic spinel-Fe nanomaterials (Fe3O4 NMs) were prepared, and then the catalase was immobilized to the Fe3O4. After, the enzyme@inorganic hybrid nanoflowers (catalase/Fe3O4@Cu2+ hNFs) were synthesized using the catalase as the organic component and Cu2+ ions and Fe3O4 as the inorganic components, defined as a catalyst. The catalase/Fe3O4@Cu2+ hNFs were characterized by using various techniques such as FT-IR, SEM, EDX, as well as XRD. The fabricated catalase/Fe3O4@Cu2+ hNFs at different pH (6.0, 7.4, 8.0, and 9.0) were tested in the reduction of nitrobenzenes and organic dye. The best results for catalase/Fe3O4@Cu2+ hNFs at different pHs were found to be 77.61%, 68.60%, 82.95%, and 91.52% with 4-nitroaniline, respectively. Herein, the effect of both pH and substrate change on the conversion of the catalytic reaction was examined. (C) 2020 Elsevier Ltd. All rights reserved.