In this study, peat was activated with H3PO4 at a concentration of 2.0 M and dried at 105oC for 6 hours. The samples after synthesis are characterized by several methods such as EDX, XRD, SEM, BET and FTIR. The adsorption properties of the materials were evaluated through the removal of Pb2+ ions in aqueous solution. Material characteristics showed that the activated peat sample had a higher specific surface area and porosity than the raw peat sample. The study showed that the experimental data of Pb2+ion adsorption on activated peat were well described according to both Langmuir and Freundlich isotherm models, however, the Langmuir isotherm model was more suitable. The activated peat material had a maximum adsorption capacity qm = 33.33 mg/g. In addition, the study also showed that the adsorption of Pb2+ ions on activated peat follows the pseudo-second-order model. From the above research results, it shows that the adsorbent material from peat has great potential in remove heavy metal ions in aqueous solution.