Summary The kinetics of the reaction of acetic anhydride (AA) and acetic anhydride in pyridine with Corsican pine (Finns nigra) sapwood have been investigated, and activation energies determined. For the pyridine catalysed system the chemical activation energy has been determined using the method of initial rates at 41.6 (±8.0) kJ/mol, and for the non-catalysed reaction as 50.9 (±3.0) kJ/mol. The reaction kinetics obey diffusion rate laws and the corresponding activation energies for diffusion have been evaluated as 20,5 (±0.9) kJ/mol (pyridine catalysed) and 34.2 (± 1.0) kJ/mol for the non-catalysed system.