As biomass feedstock, wood and lactic acid biopolymers have been used as constituents of an innovative biocomposite material possessing remarkable properties. Three different systems were made by soaking lactic acid oligomers into solid wood and then oven heating to induce in situ polymerisation, confirmed by Fourier transformed infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) analysis. Combinations of treatment systems and heating durations, implying structural wood modification, led to different physical behaviours of the composites. The first obtained material was in the form of softened and easily bendable wood. Subjected to an extended heating period, this softened material could then regain its initial hardness. Another treatment parameter combination directly led to densified wood with improved properties. These two main composite materials are expected to be useable for bending, stamping or flooring industrial uses, depending on their physical condition.