The covalent binding of laurylamine chains to maize bran heteroxylan (HX) was studied in order to produce hydrophobic plastic films. The process was carried out using periodic oxidation followed by reductive amination, both steps conducted in water. A kinetic study of the first step was performed, measuring periodate consumption, formic acid release and aldehyde formation. The over-oxidation effect was evaluated. The degree of substitution (DS) of dodecylamino-grafted-heteroxylan films ranged between 0.5 and 1.1 and varied as a function of experimental conditions. The maximal DS was reached under the following experimental conditions: NaIO4 2 eq per sugar unit, laurylamine 1.7 eq, NaBH3CN 5.8 eq per aldehyde. The plastic behaviour at room temperature was correlated to the glass transition temperature. Mechanical properties in function of the DS and the mode of obtention (casting, tape casting) were evaluated by tensile tests.