Hydrothermal treatment (HTT) was used to convert residual bacterial biomass (RBB), recovered from poly (3-hydroxybutyrate-co-3-hydroxyvalerate) production, into valuable bioproducts. The effect of processing temperatures (150, 200, and 250 degrees C) on the bioproducts (water-solubles (WSs), bio-oil, insoluble residue, and gas) was investigated. The yields of bio-oil and gas were higher at higher temperatures. The maximum WS content (28 wt%) was obtained at 200 degrees C. GCMS analysis showed higher content of aromatics and N-containing compounds with increasing temperature. ESI-MS revealed chemical compounds (e.g. protein, carbohydrate, lipids, and lignin) associated with RBB are fragmented into smaller molecules (monomers) at higher HTT temperatures. The WS fraction contained totally 838, 889 and 886 mg/g acids and 160, 31 and 21 mg/g carbohydrate for HTT at 150, 200, and 250 degrees C, respectively. The solid residues contain unconverted compounds, especially after HTT at 150 degrees C. The WS products (acids and carbohydrates) could be used directly for PHA biosynthesis. (C) 2015 Elsevier Ltd. All rights reserved.