Abstract: Water pollution by ammonium ions is considered a critical environmental issue that arises from various fast developments in industrial, human, and agricultural activities. In this study, peanut husk powder (PH), PH modified with NaOH (mPH), and its biochar modified with KMnO4 (BPH) were prepared and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) techniques. The obtained adsorbent materials were utilized for the remediation of ammonium ions from aqueous solution via batch approach. The effect of both pH, contact time, adsorbent doses, and initial ammonium concentration on the overall adsorption performance was systematically investigated. The maximum removal percentage of NH4(I) was found to be 68, 97, and 78% for PH, mPH, and BPH, respectively. Furthermore, the adsorption kinetics, and isotherms for the adsorption of NH4(I) onto all prepared three adsorbents were studied to show the behaviour of the adsorption process. The kinetic study displayed that the adsorption of NH4(I) ions onto all adsorbent materials was fitted with the pseudo-second-order model. The adsorption isotherm showed that the adsorption of NH4(I) ions was obeyed with the Langmuir model, which confirmed the formation of monolayer NH4(I) ions onto the surfaces of the adsorbent materials. For the real applications, the mPH material was utilized for the removal of NH4(I) ions from groundwater, wastewater, and a spiked Nile River sample, and the obtained data displayed a high ability of mPH toward NH4(I) ions in all investigated samples which are important for large scale applications. In addition, all prepared adsorbent materials displayed high reusability without remarkably decreasing adsorption capacity. Thus, our work proved the promising ability of high peanut husk and its derivatives to be utilized as an adsorbent for the remediation of NH4(I) ions from aqueous solutions.