Tomographic methods are well known today from medicine and non-destructive testing. However, they are also considered as promising techniques for the analysis of complex flow phenomena, for instance in chemical reactors. The investigation of hydrodynamic phenomena is of special interest in multiphase reactors such as bubble columns, separation and distillation columns, fixed bed reactors and fluidized beds in which the hydrodynamics decisively determines the heat and mass transfer as well as the global course of chemical reactions. For such applications tomography methods must be very fast because flow structures change within milliseconds in the millimeter range. With the wire-mesh sensor technology and ultrafast X-ray tomography two new imaging methods have been developed in the recent past, which fulfil these requirements. Here their functional principles and applications are described.