An electrohydrodynamic traveling-wave induction interaction is shown to pump slightly conducting liquids [electrical conductivities 10−5 to 10−15 (Ω·m)−1] without electrical contact with the flow. A gradient in fluid conductivity perpendicular to the direction of flow is required. Here, this is provided by a liquid interface, which is exposed to a traveling potential wave imposed by means of a segmented electrode parallel to the interface. Induced charges relax through the liquid to form a traveling wave of surface charge on the interface which lags the wave of image surface charges on the electrode. Hence, a time-average electrical surface traction is produced tending to make the fluid move with the traveling wave. Expressions for the fields, the time-average electric traction and the fluid velocity (in plane flow) are derived and discussed. Experiments illustrate the validity of these equations and tend to support the model used for the interfacial conduction process.