The ternary complex between benzene, ammonium ion, and formate ion has been investigated computationally. The total interaction energy is found to be much lower than the sum of the three pairwise interactions, due to nonadditive polarizations (intra- and intermolecular). The interaction with a benzene cannot stabilize the ammonium-formate complex sufficiently to avoid gas-phase collapse to the neutral formic acid-ammonia complex.