Propionic acid is an important carboxylic acid widely used in chemical, pharmaceutical, food and other industries. The growing importance of biological production (fermentation) expressed with new routes and increasing production rates, leads to look for technologies of downstream processing for product-separation. Reactive extraction with specific extractant has been the promising technique for propionic acid recovery from fermentation broth. In present work, the extraction of propionic acid with Aliquat 336 (tri(C8C10) methyl ammonium chloride) dissolved in n-heptane, petroleum ether, 1-decanol and 1-octanol respectively was investigated for various Concentrations of acid. The overall distribution coefficient (K-D), loading ratios, and equilibrium complexation constants were evaluated. The comparison with pure diluent at 305 K was also made and chemical extraction was found to be better than physical extraction. Alcohols (1-octanol and 1-decanol) when used as diluents with Aliquat 336, were found to give higher K-D values and also prevents the third phase formation which was found when Aliquat 336 was used with n-heptane and petroleum ether. Also the water co-extraction and back extraction/regeneration methods were discussed. The data obtained is useful in the designing of reactive extraction process for the recovery of propionic acid. (C) 2009 Elsevier B.V. All rights reserved.