The dynamic adsorption of a nonionic surfactant, Triton X-100(R), on Berea sandstone with radial now under a variety of injection rates, salinities and pH is examined. Mathematical modelling of the experimental data shows that the most consistent results are obtained using a kinetic hemimicelle model. The aggregation number (hemimicelle size) is independent of now rate and salinity, but increases with increasing pH. In all cases, the aggregation number is lower under dynamic conditions than under static conditions, which is attributed to the shear force at the surface. The rate constants for adsorption increase with increasing now rate, which is attributed to a decrease in mass transfer resistance.