Modifying cellulose nanofiber (CNF) is necessary to improve its hydrophobic properties for broader applications. The surface of CNF from the banana pseudo-stem (Musa paradisiaca) was modified using a cationic surfactant, Cetyltrimethylammonium Bromide (CTAB). Principally, CNF surface sulfate ester group counterions are substituted for cetyltrimethylammonium (CTA+), which acts as a bulky, amphiphilic cation. Three steps produce CNF from banana pseudo-stem: delignification, bleaching, and acid hydrolysis. The acid hydrolysis process was optimized by adjusting the concentration of sulfuric acid. A 50% sulfuric acid concentration produced CNF with a size of 118 nm and the highest stability of its zeta potential value of -28.4 mV. The hydrophobicity of CNF increased after CTAB modification, as demonstrated by a change in surface charge from -28.4 mV to +3.63 mV. The modified CNF50-CTAB had a contact angle of 45.5º. In addition, CNF50-CTAB was unstable in water and formed stable colloidal suspensions in chloroform.