Abstract Olive pomace is a by-product of olive oil production and an important biomass for the Mediterranean countries. The aim of this study was to optimize the oil extraction from olive pomace by supercritical CO 2 and utilize the remaining biomass by hydrolysis. A Box–Behnken statistical design was used to evaluate the effect of temperature (30–80 °C), pressure (120–300 bar) and CO 2 flow rate (10–20 g/min) for 60 min. The most effective variable was pressure ( p 2 (SC-CO 2 ) and hexane de-oiled pomaces were subjected to acid and enzymatic hydrolyses. Hydrolyses with 2% of sulfuric acid for 90 min yielded 12.30 and 12.65 g/l reducing sugar from SC-CO 2 and hexane treated biomasses, whereas the highest reducing sugar concentrations achieved with enzymatic hydrolysis with a substrate amount of 6 g, 20–27% Cellic CTec2/Novozyme 188 for 24 h were 12.72 g/l and 10.13 g/l, respectively. A holistic engineering approach is proposed where supercritical CO 2 can be used as a main process to extract remaining oil in olive pomace and as a pretreatment loosen the structure in order to obtain liquor which can be converted to a biofuel.