A Pseudomonas sp. capable of growing on p-fluorophenylacetic acid as sole carbon source has been isolated using the enrichment culture technique. All the organic fluorine is released into the culture medium as fluoride ion during growth. A number of fluorinated intermediates have been isolated from the culture medium when resting cells were incubated with the substrate. Using infrared, nuclear magnetic resonance, and mass spectroscopic techniques together with chemical degradative procedures, these have been identified as D(+)-monofluorosuccinic acid, trans-3-fluoro-3-hexenedioic acid, (−)-4-carboxymethyl-4-fluorobutanolide, 4-fluoro-2-hydroxyphenylacetic acid, and 4-fluoro-3-hydroxyphenylacetic acid.