In this paper, we describe the characterization and application of adsorbent derived from the pyrolysis of cocoa shells, which is a natural source of adsorbent materials. The adsorbent that was used in this experiment is an environmentally friendly adsorbent that was prepared by the pyrolysis of cocoa shells. For 1.5 hours, the pyrolysis process was carried out at temperatures ranging from 300 to 380 °C. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and analysis with an X-ray diffraction (XRD) analyzer. Water-ash content and iodine absorption capacity were also determined in accordance with SNI 06-3730-1995. At a contact time of 90 minutes, the adsorption capacity of mercury ions was found to be 0.106 mg/gram. In this study, the adsorption of mercury ions with the adsorbent followed pseudo-second-order models with an R2 value of 0.9929.