The goal of this study is to remove bitterness of cold pressed grapefruit seed oil by adsorbent treatments. The oil is treated with amberlites XAD7, IR120, and IRA400 resins, and natural zeolite, sepiolite, and montmorillonite at 3% (w/w) level. Oil physicochemical properties, oil flavonoid, phenolic acid and phytosterol compositions, oil sensory descriptive analysis, oil consumer preferences as well as properties of the adsorbents are determined. The largest surface area, pore radius, pore volume, and oleic acid adsorption capacity are observed for natural sepiolite, zeolite and XAD7 amberlite. Adsorbent treatment usually reduced oil viscosity, free acidity, and soap content. In removal of flavonoids, natural sepiolite, zeolite and XAD7 resin are the most successful. Reductions from 3.0 to 60.0% are quantified. Phytosterol composition is not changed significantly by adsorbent treatment. Quantitative sensory descriptive data shows that natural sepiolite at first, followed by natural zeolite and amberlite XAD7 reduced bitterness and throatcatching scores almost by half, but consumer preference test results shows that these reductions were not enough for consumers to accept the taste/flavor of the treated oils. Hence, bitterness removal from grapefruit seed oil still remains as a research challenge.