Waste citrus peels can be used as source of several bioactive compounds. Among these, D-limonene is the Received 2 July 2014 major constituent in lemon essential oil and is of great interest in several fields.With the aim of optimiz- Received in revised form 4 September 2014 ing D-limonene extraction from lemon peels after citrus processing, a non-conventional solvent extrac- Accepted 5 September 2014 tion was studied. Hexane was used as solvent at high pressure and temperature and influence of Available online 28 September 2014 extraction time, temperature–pressure and matrix/solvent ratio (M) on yield of D-limonene was analyzed 3 by a statistical approach applied to a three-level full factorial design (3 ). The highest yield was reached Keywords: when extraction was performed with M = 1:15 at 150 C for 30 min (3.56%). Furthermore, a response sur- D-limonene face methodology (RSM) was used and experimental results were fitted by a second-order polynomial Lemon peels equation. The effects of drying pre-treatment and particle size were also evaluated in this work. The Solvent extraction effectiveness of this innovative method in extraction of citrus essential oils – and, in particular, of D-lim- High pressure onene – has been evaluated and compared to conventional Soxhlet extraction. High pressure – high tem- High temperature perature extraction (HPTE) of D-limonene from lemon peels was better than Soxhlet extraction even with Response surface methodology low matrix/solvent extraction (1:4) in terms of energy saving (0.6kW h vs 2.5kW h), extraction time (30 min vs 4 h) and product yield (2.97% vs 0.95%).