A novel yolk-shell-structured material (Fe3O4@gamma-AlOOH-YSMs) with hierarchical gamma-AlOOH flakes as the mesoporous shell and Fe3O4 nanoparticles (NPs) in the hollow core was prepared by using Fe3O4@SiO2 NPs as the seeds as well as NaAlO2 and urea as the precursor. The prepared Fe3O4@gamma-AlOOH-YSMs were used as a catalyst support for fabricating a Pd/Fe3O4@gamma-AlOOH-YSMs nanocatalyst with no obvious aggregation of the Pd NPs. The Pd/Fe3O4@gamma-AlOOH-YSMs nanocatalyst was utilized for the catalytic reduction of the widely used and highly toxic 4-nitrophenol, rhodamine B, methylene blue, and methyl orange; and showed excellent catalytic activity as compared with other noble-metal-based catalysts. Furthermore, the Pd/Fe3O4@gamma-AlOOH-YSMs nanocatalyst also can be easily separated from the reaction mixture and reused for at least ten times without any obvious decrease in the catalytic activity, indicating its reusability and stability. (C) 2017 Elsevier B.V. All rights reserved.