Whole yeast cell reductive biotransformation of a benzylidene thiazolidinedione to its corresponding benzyl derivative has been scaled up from laboratory to small pilot plant scale. The fermentation conditions for the yeast Rhodotorula rubra were examined and cell titres increased by optimising the medium. Problems encountered in handling substrates of low water solubility are discussed. Various techniques are described for adapting the procedure for process scale operation using the general principles of process scale-up and integration. Liquid-liquid extraction using a dense solvent was performed on whole broth systems using a continuous flow liquid-liquid separator. Fatty acid impurities were removed using selective solvent extraction.