The effect of Silver-Indium-Cadmiun (SIC) control rod on the transport of volatile fission products (I, Cs, Mo) in conditions of a Reactor Coolant System under NPP severe accident was investigated within three semi-integral tests in a thermal gradient tube. The experiments addressed separately the effect of each SIC element. Nature of transported and deposited species was investigated by ICP MS, ESEM-EDX, Raman Microspectrometry, XRD and XPS techniques. For the first time, numerous metallic molybdates involving SIC components were evidenced. The formation of such metallic molybdates competes with the formation of Cs-molybdate and may in certain conditions strongly reduce the scavenging effect of Mo towards Cs. As a result the nature of transported iodine can be strongly modified, compared to chemical systems involving only Mo, Cs and I. The data obtained are useful to guide what species have to be added in the thermodynamic database used in the SA simulation software.