Cellulose-enriched residues from wheat bran can be transformed in bio-plastics after esterification of the cellulose by lauroyl chloride. Before the esterification reaction, an activation step with a swelling of the sample in dilute acid and subsequent drying was required. This activation had a marked influence on the amount of esterified product and its degree of substitution. Using pure cellulose as well as cellulose-enriched agricultural residues, we have shown that the cellulose was totally recovered after this pretreatment and that partial hydrolysis of cellulose chains occurred during the drying step, which probably improved the accessibility to chemical reagents. The possible role of sulfuric acid as catalyst for the esterification reaction of the cellulose by lauroyl chloride was discussed.