Keywords: Streaming potential, multiphase flow, porous media Abstract: Streaming potentials generated by single phase flow are reasonably well-understood, but much less is known about the effects of multiphase flow. The introduction of a second fuid phase can either increase the wall shear rate (thereby increasing streaming currents caused by convection of ionic charge clouds), or can decrease it, depending on the ratio of the viscosities of the two phases and on the effect of interfacial tension. If the second phase is non-conducting (e.g. oil droplets in water), the effective conductivity of the mixture is decreased, and streaming potentials tend to increase. I shall review the few experimental results that are available, and describe recent theoretical work aimed at understanding the effect of a single particle or fluid droplet flowing through a capillary. J.D. Sherwood, Streaming potential generated by two-phase flow in a capillary. Phys. Fluids, 19 (2007) 053101. J.D. Sherwood, Streaming potential generated by a long viscous drop in a capillary. Langmuir, 24 (2008) 10011. E. Lac & J.D. Sherwood, Streaming potential generated by a drop moving along the centreline of a capillary. J. Fluid Mech. (in the press)