The paper reports on labscale column studies for in situ surfactant washing of oil-contaminated soils. The displacment efficiency of nonionic surfactants and their blends was tested on small columns. The kinetics of oil displacement and surfactant sorption-desorption were studied. Further, the viscosity behavior of emulsions of varying compositions was investigated. No single optimum HLB value was found for the displacement of a selected oil. It depends on the surfactant pair chosen. Optimum surfactant composition is distinctly different for weathered and unaltered diesel oil. The application of single nonionic surfactants leads to a substantial reduction of soil permeability or even to clogging. This is due to formation of viscous emulsions. This can be avoided by using surfactant blends. This way, the complex requirements for insitu application, i.e., maintenance of permeability, low surfactant losses, and low residual levels of oil can be achieved.