In order to find alternative low-cost adsorbents for volatile organic liquids, the effectiveness of nickel oxide nanoparticles-modified diatomite (NONMD) in removing benzene was assessed. The impact of different operation parameters such as pH, contact time, initial benzene concentration, and adsorption dosage on the adsorption process was evaluated and optimum experimental conditions were identified. Surface area and morphology of the nanoparticles were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) isotherms, X-ray diffraction (XRD), Fourier transform infrared (FTIR), and energy dispersive X-ray (EDX) analysis. The isotherm and kinetics effect of the adsorbent were evaluated.