Olive tree trimmings (OTT) were subjected to sequential stages of autohydrolysis (with hot compressed water) and ethanol water mixtures (organosolv pulping), to obtain three separate streams containing hemicellulose-derived products (autohydrolysis liquors), lignin fragments (pulping liquors), and autohydrolyzed, delignified solids (denoted ADOTT) mainly made up of cellulose. Up to 42% of the polysaccharides contained in the raw material (accounting for about 25% of the OTT dry mass) were recovered in autohydrolysis liquors as valuable compounds, whereas ADOTT showed high susceptibility toward enzymatic hydrolysis and allowed the formulation of media in which saccharification and ethanol fermentation were carried out simultaneously at a high product yield. Ethanol conversions higher than 90% of the theoretical value (calculated from the AD OTT content of cellulose) were achieved, whereas the ethanol concentration of fermented media reached values up to 39 g/L.