Fique is a plant widely produced in Colombia; its fibers are mainly used in the production of packaging, the fique industry produces large amounts of a residue called fiber dust, this residue preserves the properties of the fiber, and however it is discarded without any type of use. In this study, a surface modification consisting of the esterification of fique dust was carried out. Alkalinization was performed to eliminate the hemicellulose present in fique dust in order to facilitate the identification of new carbonyl groups in the FTIR. The esterification of the fique dust was carried out using oxalic acid as a couple agent in a green solvent. The modified fique dust was characterized by the use of spectroscopic (FTIR-ATR) and thermal (TGA, TGD) techniques. The results of the spectroscopic analysis revealed the presence of new carbonyl groups at 1731 cm−1, indicating that the esterification reaction was successful. The thermal analysis shows the elimination of hemicellulose from the fique dust after the alkaline treatment, in addition, revealed a decrease in the thermal stability of the fique dust with alkaline treatment and an increase in the thermal stability of the esterified fiber. The esterified fique dust shows an improvement in its solubility in DMSO.