Raman. infrared and SERS (on silver colloid) of akacid have been investigated. The experimental Raman and infrared data is supported with DFT calculations using B3LYP functional and 6-311 G** and LANL2DZ basis sets. The vibrational frequencies of the molecule and its silver complex were computed at the optimized geometry and compared with the experimental values. This is the first report on the vibrational analysis of akacid, its anion and its silver complex. From the most enhanced bands observed in the SERS spectrum as well as theoretical calculations, it has been inferred that the molecule is chemisorbed to the silver surface through the oxygen of the carboxylate group with interactions from the nitro group and also the ring pi-electrons. (C) 2004 Elsevier B.V. Ail rights reserved.