Quantitative determination of thiosulphate, thiocyanate and thiourea ions spectrophotometrically has been investigated. The high absorptivity of the investigated ions-nitroprusside complexes at the optimum conditions indicates that concentrations of 10−4–10−3M of thiosulphate, thiocyanate and thiourea can be determined spectrophotometrically with fair accuracy. The effect of pH was studied and the optimum pH was determined to give the highest sensitivity. The validity of this method is supported by the constancy of the molar absorptivity.