A few photosynthetic bacteria have been isolated from a biological treatment system treating producer gas plant effluent. One of them was identified as Rhodopseudomonas gelatinosa on the basis of physiological and morphological characteristics. Biodegradation of aromatic compounds by R. gelatinosa appears not to have been reported in the literature. The culture was found to degrade benzoic acid, p-hydroxybenzoic acid, cinnamic acid, and p-coumaric acid. The doubling time for this culture was found to be 18, 19, 23, and 31 h for benzoic acid, p-hydroxybenzoic acid, cinnamic acid, and p-coumaric acid respectively.