The method is based on the reduction of chlorine by an electrophilic coupling reagent, 3-methyl-2-benzothiazoline hydrazono hydrochloride hydrate (MBTH) and subsequent coupling with NEDA. An improved method using N-1-Napthylethylenediamine dihydrochloride (NEDA) as a chromogenic reagent for determination of residual chlorine is proposed. The blue color formed in the reaction showed maximum absorbance at 610nm and obeyed Beer’s law over the range 0.3-4.2ppm. The molar absorptivity and Sandell’s sensitivity values were 3.14×10³ L mol^-1cm^-1 and 0.102µg cm^-2 respectively. The performances of proposed methods were evaluated in terms of student t-test and variance ratio F-test which indicated the significance of proposed methods over the reference spectrophotometric method. The proposed methods were successfully applied in determination of residual chlorine in drinking water and environmental water samples.