A review of advanced measurement techniques in gas-liquid-solid systems is presented. Most GLS systems are operated at relatively high volume fractions. This makes the systems opaque and less suited for investigations based on laser application. Several measuring techniques have been developed to deal with non-transparent systems. Amongst these are Electrical Capacitance Tomography, X-ray CT scanning and Magnetic Resonance Imaging. This contribution discusses some of the recent development and identifies the directions research is taking.