The catalytic wet air oxidation (CWAO) of lignin, obtained from sugar-cane bagasse, was evaluated through kinetic studies of the process of aromatic aldehyde production. The operations were carried out in a high pressure mechanically stirred slurry reactor, in a semibatch way, and in the presence of a palladium catalyst supported on gamma-alumina in a temperature range of 373-413 K, at a total pressure of 20 bar, where the partial pressure of oxygen varied in a range of 2-10 bar. The lignin concentration was 60.00 kg/m(3) in an alkaline medium of 2 mol/L of NaOH. The lignin degradation reaction and the aromatic aldehyde buildup were described by a kinetic model quantified by a complex series/parallel reaction network.