The continuous hydrolysis of bovine haernoglobin at pH 3 in a triphasic reactor was studied in order to prepare two pure transient and hydrophobic opioid peptides in one step. A continuous stirred-tank reactor was designed to extract continuously and selectively LVV-haemorphin-7 and VV-haemorphin-7 by a butan-2-ol-octan-l-ol mixture in the course of bovine haernoglobin hydrolysis by pepsin immobilised on A568 Duolite resin. The residence time in the aqueous and organic phases was maintained at 1 h. This system allowed a steady state to be achieved for haemorphin concentrations in each phase and the pepsin stability to be maintained. Finally, success was achieved in producing and extracting continuously the two haemorphins in the aqueous/butan-2-ol-octan-l-ol biphasic medium for more than 10 bed volumes of the reactor. (c) 2006 Society of Chemical Industry.