Kinetic studies of the reaction of brilliant green with alkalies have been made by following the reaction spectrophotometrically at 625 mμ. The reaction has been found to be bimolecular but under experimental condition of excess alkali, it obeyed a first order law. The rate constants was independent of the concentration of brilliant green but it varied linearly with the hydroxyl ion concentration. Effect of neutral salt on the rate of reaction was investigated in aqueous and in 40% acetone-water media. The rate was found to decrease progressively with increasing ionic strength in both media. Analysis of the data by Brφnsted-Christiansen-Scatchard equation yielded a value of −1 for ZaZb indicating thereby that the rate-determining step involves oppositely charged species possessing unit charge. The value of inoic interaction parameter, ai corresponded to 1.5 and 4.75 Å in aqueous and 40% acetone-water medium respectively. Without attaching too precise a meaning to ai it is suggested that B.G. ion is presumably solvated to a greater extent in 40% acetone-water than pure water.