Using a laser monitoring observation technique, solubilities of o-nitro-benzoic acid, p-hydro-benzoic acid, p-methyl-benzoic acid and m-methylbenzoic acid in water have been measured in the temperature range 290.15-323.15 K. The experimental data are regressed with the Wilson equation and the; H equation. The experimental results show that solubilities of these compounds in the range of 10(-4)-10(-5) mole fraction in water, increase significantly with temperature. Except for o-nitro-benzoic acid, the solubility data are described adequately with the Wilson equation. The lambda H equation gives good agreement with all experimental data. The results indicate that the molecular structure and interactions affect the solubilities significantly. (c) 2006 Elsevier B.V. All rights reserved.