The penetrating power of X-rays coupled with the high flux of 3rd generation synchrotron sources makes X-ray tomography to excel among fast imaging methods. To exploit this asset of synchrotron sources is the motivation for setting up an ultra-fast tomography endstation at the TOMCAT beamline. The state of the art instruments at synchrotron sources offer routinely a temporal resolution of tens of seconds in tomography. For a number of applications, for example biomedical studies, the relevant time scales (breathing, heartbeat) are rather in the range of 0.5-2 seconds. To overcome motion artifacts when imaging such systems a new ultra-fast tomographic data acquisition scheme is being developed at the TOMCAT beamline. We can acquire a full set of projections at sub-second timescale in monochromatic or white-beam configuration. We present a feasibility study with the ultimate aim to achieve sub-second temporal resolution in 3D without significant deterioration of the spatial resolution. For the first time, the 3D dynamics of the very early stages of a quickly aging liquid foam can be visualised with high quality and sufficiently large field of view.