The detergency of the alkaline ionized liquid of pH 9.6 was compared with that of the ion exchanged water (pH 5.8) and the acid ionized liquid (pH 2.9) by applying DLVO theory. Polystyrene latex particle and sodium dodecyl sulfate (SDS) were considered to the fiber and the solid particle charged with negative ions in water respectively. It was supposed that the potential barriers of adsorption and desorption corresponded to the adsorption and desorption rate constants (ka, kd). The two constants (ka, kd) of SDS to and from polystyrene latex were determined through the stopped-flow technique. The adsorption rate constants were 10.6×104, 3.55×104 and 8.44×104 mol-1dm3s-1, the desorption rate constants were 8.43, 8.62 and 9.29 s-1, the values of ka/kd were 1.26×104, 4.12×103 and 9.09×103 mol-1dm3 and the standard free energy change (ΔG) was -7.84, -7.19 and -7.65 kcal mol-1 for the ion exchanged water, the alkaline ionized liquid and the acid ionized liquid respectively. The adsorption rate constants were dependent upon the water hardness of the used liquids and the desorption rate constants were dependent upon ζ-potential of polystyrene latex particles in the liquids. The smaller the value of ka/kd was, the more the washing condition was effective. The detergency of the alkaline ionized liquid was determined by comparison with ΔG of the other liquids. It was made clear that the detergency of the alkaline ionized liquid was 1.09 times of the ion exchanged water and 1.07 times of the acid ionized liquid.