The adsorption of C12E8 onto a clean air-water interface is studied by using a video-enhanced pendant bubble tensiometry. The controlling mechanism for mass transfer changes as a function of bulk concentration; it shifts from diffusion control at dilute concentration to mixed diffusion-kinetic control at more elevated bulk concentration. The adsorption of C 12E8 is found to be anticooperative from the equilibrium surface tension data compared with the prediction of the (generalized) Frumkin model. Relaxation profiles of surface tension for C12E8 molecules absorbing onto a freshly created air-water interface for 21 different bulk concentrations are obtained. Comparison is made for the entire relaxation period of the tension data and the model predictions. Values of the diffusion coefficient and the adsorption/ desorption rate constants of C 12E8 are calculated from these dynamic surface tension profiles.