The catalytic potential of sludge based materials produced by steam or CO2 activation from non-treated dewatered raw sludge or dewatered mesophilic anaerobically digested sludge were tested in the oxidation of phenol. Batch and continuous experiments were conducted to assess activity and stability of these novel carbons in terms of phenol conversion, carbon burn-off and metal leaching. Overall, their catalytic activity can be considered satisfactory when compared to commercial carbons. However, further research on the preparation, activation and hardening of these sludge based materials is required to improve their thermal and mechanical stability and resistance to metal leaching during the catalytic wet air oxidation of phenol.