Dynamic interfacial tension between aqueous solutions of 3-dodecyloxy-2-hydroxypropyl trimethyl ammonium bromide (R(12)HTAB) and n-hexane were measured using the spinning drop method. The effects of the R(12)HTAB concentration (the concentration below the CMC) and temperature on the dynamic interfacial tension have been investigated: the reason of the change of dynamic interfacial tension with time has been discussed. The effective diffusion coefficient, D-a, and the adsorption barrier, epsilon(a), have been obtained from the experimental data using the extended Word-Tordai equation. The results show that the dynamic interfacial tension becomes smaller while epsilon(a), becomes higher with increasing R(12)HTAB concentration in the bulk aqueous phase. D-a decreases from 5.56 x 10(-12) m(-2) s(-1) to 0.87 x 10(-12) m(-2) s(-1) while e increases from 5.41 kJ mol(-1) to 7.74 kJ mol(-1) with the increase of concentration in the bulk solution of R(12)HTAB from 0.5 x 10(-3) mol dm(-3) to 4 x 10-3 mol dm(-3). Change of temperature affects the adsorption rate through altering D-a and epsilon(a). The value of D-a increases from 5.56 x 10(-12) m(-2) s(-1) to 13.98 x 10(-12) m(-2) s(-1) while that of epsilon(a) decreases from 5.41 kJ mol(-1) to 5.07 kJ mol(-1) with temperature ascending from 303 K to 323 K. The adsorption of surfactant from the bulk phase into the interface follows a mixed diffusion-activation mechanism, which has been discussed in the light of interaction between surfactant molecules, diffusion and thermo-motion of molecules. (c) 2008 Elsevier B.V. All rights reserved.