In this study, locally sourced clay material and peat moss were investigated as low-cost adsorbents for retention of Hg(II) ions from aqueous solutions. The optimum adsorption conditions were obtained at pH 2.0, an adsorbent dose of 4 g/L, a contact time of 5 min, an initial Hg(II) concentration of 320.32 mg/L in the case of clay materials and at pH 6.0, an adsorbent dose of 4 g/L, a contact time of 5 min, an initial Hg(II) concentration of 523.38 mg/L in the case of peat moss. The practical effectiveness and enhanced potential of the clay and peat moss material as an adsorbent for treating aqueous effluents have been demonstrated by fitting the experimental data using pseudo-first-order and pseudo-second-order kinetic models.