Аннотация:The aim of the presented research paper was to modify the biofiller in the form of milled cereal straw with 3-aminopropyl(diethoxy)methyl silane, and apply it to the natural rubber. To determine the material properties, an in-depth characterization of both the treated lignocellulosic material and the composites was studied. On the basis of thermogravimetric analysis, scanning electron microscopy, infrared spectroscopy and analysis of contact angle measurements, it was found that the silanization process significantly influenced thermal stability and hygroscopicity of the straw, its hydrophobicity as well as dispersion in polymeric matrix. Analyses of the new composites included static and dynamic mechanical properties, hardness, and barrier and damping properties, all of which showed improvement. This was because of improved interactions at the filler–elastomer, which resulted from better adhesion of the treated bio-additive to natural rubber. Biocomposites have also demonstrated greater resistance to flammability as well as thermo-oxidative aging processes. The research clearly indicates the application potential of these new multifunctional and biocompatible materials.