Contamination of water resources by nitrate has become an important problem in recent decades. Although nitrate is not toxic, it can be converted into nitrite and cause serious harm to human health. One of the most effective methods of nitrate removal is the use of adsorbents. The objective of this study was to evaluate the nitrate adsorption efficiency from biogas solution by using melaleuca biochar that was pyrolysed at 700oC. Physical and chemical characteristics of melaleuca biochar were determined using a variety of methods including scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) test. Nitrate concentration was measured using a UV spectrophotometer with a wavelength of 660 nm. The results showed that the optimum conditions for the effective adsorption of nitrate ion onto melaleuca biochar were found to be pH 4, biochar dosage of 1 g L-1, and retention time of 15 min. The experimental data were fitted to different adsorption isotherms models (Langmuir, Freundlich models). The maximum nitrate adsorption capacity of melaleuca biochar was 15.5 mg g−1.