A novel copper-based catalyst supported by a long-chain hydrocarbon stearic acid (Cu x O@C18H36O2) was synthesized by a hydrothermal method and double replacement reactions. The as-prepared catalyst is shown as self-assembled hierarchical nanoflakes with an average size of ∼22 nm and a specific surface area of 51.4 m2 g-1. The catalyst has a good performance on adsorption as well as Fenton-like catalytic degradation of Rhodamine B (RhB). The catalyst (10 mg/L) showed an excellent adsorption efficiency toward RhB (20 mg/L) for pH ranging from 5 to 13, with the highest adsorption rate (99%) exhibited at pH 13. The Fenton-like catalytic degradation reaction of RhB (20 mg/L) by Cu x O@C18H36O2 nanoflakes was effective over a wide range of pH of 3-11, and •OH radicals were generated via Cu2O/H2O2 interactions in acidic conditions and CuO/H2O2 reactions in a neutral solution. The highest efficiency catalytic degradation of RhB (20 mg/L) was 99.2% under acidic conditions (pH = 3, H2O2 = 0.05 M), with an excellent reusability of 96% at the 6th cycle. The results demonstrated that the as-prepared Cu x O@C18H36O2 nanoflakes are an efficient candidate for wastewater treatment, with excellent adsorption capacity and superior Fenton-like catalytic efficiency and stability for RhB.