The overall objective of this study was to investigate the performance of the supercritical water oxidation (SCWO) technology for the treatment of wastewater sludge, and investigate the degradation of p-tert-butylcatechol (TBC) which is a recalcitrant organic compound. The first phase of the study focused on the optimization of the thickening process that precedes SCWO, and investigated the impact of sludge temperature (10 oC -100 oC) on the optimum polymer dose and conditioning of wastewater sludge. In the second phase, SCWO treatment of sludge was investigated under a range of operational conditions including sludge solids content (2-12 %), TBC concentration (0.1-1 %), reactor temperature (400-550 oC), reactor pressure (18-28 MPa), oxygen excess (n=1-8) and residence time (1-30 minutes). The results showed that SCWO is a very effective process for sludge treatment and degradation of recalcitrant organic compounds in sludge.