The nanofibrils of 4–6 nm in diameter and several μm in length were isolated. Composites polyacrylic acid/β-chitin were prepared by polymerization in situ. Prepared nanocomposites revealed superb mechanical properties at high humidity. Polyacrylic acid and β-chitin in composite are chemically crosslinked. Percolation threshold is reached at composite of 3% of chitin.