The equilibrium and dynamic surface tension data are widely utilized to investigate the information of intermolecular interactions between the adsorbed surfactant molecules, the adsorption kinetics, and the mass transfer coefficients. In this paper, a concept is explored : using only a limited range of equilibrium surface tension data to determine the adsorption isotherm can cause a serious mistake on the determination of adsorption kinetics and/or on the evaluation of diffusion coefficient from the dynamic surface tension data. This idea is illustrated theoretically for clean interface adsorption on a pendant bubble or drop using the Langmuir and Frumkin adsorption models. Two types of surfactant, one with cooperative adsorption behavior and the other with anticooperative adsorption behavior, are discussed. This concept is further demonstrated using the relaxation data of surface tension of 1-octanol.