In this work, a hydrophobic cellulose aerogel was successfully developed from coir fibers waste. The hydrophobic aerogel was prepared using a simple sol-gel and freeze-drying method followed by surface modification using either trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDS). The operating temperature was varied around the boiling point of the modifying agent ranging from 50-70 C for TMCS and 110-130 C for HMDS. The concentration of modification agents was varied from 40-60 wt.% in n-Hexane. The best condition in term of its hydrophobicity was obtained at 50% of TMCS with a temperature of 60 C and 40% of HMDS at 120 C. The obtained aerogel has a good hydrophobic characteristic indicated by a high of water contact angle of 100-150 C. The aerogel also could selectively absorb only oil from the mixture of oil-water. Therefore, it could be the promising material used to overcome the oil spill issue due to its biodegradability, abundant availability, and low cost.