The thesis project deals with the experimental characterisation and qualitative understanding of the electronic and magnetic properties of spin-orbit assisted Mott insulators. Spin-orbit assisted Mott insulators are transition metal compounds of the 4d and 5d series whose physical properties are crucially affected by simultaneous strong electron correlation and spin-orbit coupling. Examples are oxides of iridium, osmium and rhenium. The experimental activity uses mainly X-rays and is carried out at various synchrotron facilities, but mostly at ESRF - The European Synchrotron (Grenoble, ESRF).