Hierarchical mesoporous copper oxide nanoflakes (CuOs) were successfully synthesized by hydrothermal method. The complete characterization of product was done by XRD, SEM, TEM, SAED, EDX, BET and FT-IR studies. The batch experiments were conducted under different adsorbate concentration, contact time, pH and temperature conditions. The residual analyte concentration was determined using differential pulse anodic stripping voltammetry (DPASV) technique with high accuracy and reproducibility. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. Equilibrium data were best fitted with the Langmuir and Freundlich isotherm models and the maximum adsorption capacities of Hg(II) and Cd(II) were determined to be 1767.97 and 1577.78 mg/g respectively. All these values are significantly higher than those reported on other hierarchical nanostructures. Thermodynamic parameters and adsorption kinetics were studied in detail to know the nature and mechanism of adsorption. A regeneration study is proposed in order to reuse the adsorbent for better economy of the process. The results demonstrate that CuOs can be used as a possible alternative low-cost adsorbent for the efficient removal of heavy metals from aqueous solutions. (C) 2014 Elsevier B.V. All rights reserved.