A simple chemical modification route to confer high hydrophobicity to crystalline cellulose surface was demonstrated using tunicin whiskers as model material. An alkyenyl succinic anhydride (ASA) aqueous emulsion was mixed with cellulose suspension, freeze-dried, and heated to 105 °C. The bulk degree of substitution (DS) was evaluated by FT-IR spectrometry, elemental analysis, and weight gain. The surface DS was quantified by X-ray photoelectron spectroscopy. The surface-acylated whiskers retained their morphological and crystalline integrity, but due to their surface acylation, they are readily dispersible in solvents of low polarity such as 1,4-dioxane. These whiskers can also be well dispersed in polystyrene to form a nanocomposite.