Hydroxytyrosol is extracted from olives and/or from the solid residues of olives after the extraction of olive oil, by carrying out acid hydrolysis at a temperature within the range of 110.degree. C. to 140.degree. C. and at a pH within the range of 1.0 to 6.0, and by purifying the obtained solution on a column containing acid activated anion exchange resins, and a column containing an adsorbent non-ionic resin; both columns being eluted with water to recover the hydroxytyrosol.