Precise inline process analysis, as an instrument for securing product qualities and enhanced process efficiency, nowadays often requires not only a temporal but also a spatial investigation of relevant physical process parameters. From the variety of available methods that allow for a tempo-spatial medium analysis, the ultrasonic-based tomographic approach and its direct application for inline monitoring of liquid systems is discussed in the present contribution. As an application example, the localization and characterization of an a priori unknown multiphase layer system has been performed by means of a simple ultrasonic transmitter–receiver arrangement. The data acquisition is based on the ultrasonic waves that are transmitted through the medium under test. Those signals represent the input of the tomographic process imaging. Using a linear model describing the homogeneous wave propagation and a fast estimation algorithm running on a normal PC, the extraction of information regarding layer thicknesses, materials and boundary properties has been performed in real time. The corresponding results are verified by simulations and semi-numeric studies and are additionally confirmed by first experimental tests.