Cottonseed oil is consumed either in raw state or after refining, which enables it to acquire the characteristics such as neutral taste and odor, limpidity, light color, oxidation stability to oxidation, and for it to be used for frying. Refining comprises several strategies including bleaching, which involves the fixation of beta-carotene, the pigment that is responsible for the red color of cottonseed oils, on a solid support generally known as bleaching earth. In this work, possible application of locally available clay (Ordu, Turkey) as bleaching earth was investigated for cottonseed oil refining. Raw clay was activated via various treatment methods including acid activation, cation treatment and thermal treatment. Structural changes caused by acid activation were characterized using Fourier transform infrared spectroscopy, differential thermal analysis, N(2) adsorption (BET surface area), X-ray fluorescence and scanning electron microscopy. Bleaching capacities of the treated clays were also determined spectrophotometrically. Bleaching efficiency was increased from 3 (raw clay) to 23% by H(2)SO(4) activation and to 34% by Al(3+) and heat treatment. However, commercial clay's efficiency was 32%. Tetrahedral destruction with proton attack was higher in HCl solution than H(2)SO(4) solution, resulting in collapse in micropores. Bleaching efficiency increment using H(2)SO(4) was higher than that of HCl.