A new thiosemicarbazone, benzildithiosemicarbazone (BDTSC), is proposed as a sensitive and selective analytical reagent for extractive spectrophotometric determination of Cd(II). BDTSC reacts with cadmium(II) to give a yellow-colored complex in ammonium chloride-ammonium hydroxide buffer of pH 10.5, which is easily extracted into isoamylalcohol with 1:1 composition having a maximum absorbance at wavelength 360 nm. The molar absorptivity and Sandell's sensitivity are found to be 0.196 x 10(4)dm3 mol(-1)cm(-1) and 0.008 microg cm(-2) of Cd(II), respectively. The instability constant of the method has been calculated by Asmus' method as 5.05 x 10(-5) (which is in close agreement with the value obtained by Edmonds and Birnbaum's method) at room temperature. The interfering effect of various cations and anions has also been studied. The method has been successfully applied for the determination of Cd(II) in several standard reference materials as well as environmental samples, medicinal leaves and leafy vegetables.