Phosphorus (P) recovery from P-rich residues such as sewage sludge (SS) is crucial to sustain food and industrial demands globally. This study investigated the speciation and recovery of P from SS after hydrothermal carbonization (HTC). Treatment with organic acid solutions at different pH conditions was investigated to determine how the composition of SS and hydrochars affect the P and major metals release. HTC experiments at 180, 215 and 250 °C showed that P remained immobilized(>75% of total P) in the hydrochars and that almost all of that P was present as inorganic P. Extraction efficiencies of P and major metals decreased with increasing pH, with maximum extraction efficiency reached in the pH range of 0-1 for oxalate and 0 for citrate and HCl, demonstrating that HCl is only effective for P and metal dissolution at extreme low pH. Oxalate treatment was found to have higher P release and metal leaching compared to citrate. Moreover, P and major metals extraction seems to have no clear difference between hydrochars generated at different HTC temperatures (180, 215 and250 °C) for 2 h extraction time. Kinetic studies with oxalate solution at pH=1.4 showed that P recoveryat lower HTC temperature is the most time-efficient.