A novel, rapid, highly sensitive and selective spectrophotometric method was developed for the determination of traces of selenium (IV). The method is based on direct oxidation of leuco methylene green (LMG) with selenium (IV) in acetate buffer at pH 4.0±0.2 to give blue colored derivative with λmax 624 nm and the colored product is stable for more than 7 days at 350C. Beer’s law is obeyed for selenium (IV) in the concentration range of 0.25-2.5 μg ml-1 at the wavelength of maximum absorption. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The detailed study of various interferences made the method more selective. The proposed method was successfully applied to the analysis of selenium in various environmental samples. The results obtained were good agreement with the reported methods at the 95 % confidence level. The performance of proposed method was evaluated in terms of student’s ttest and variance ratio f-test which indicates the significance of proposed method over reported method.