Experimental determination of the thermophysical properties (thermal and electrical conductivity, viscosity, and surface tension) of lithium iodide was carried out in the temperature range starting slightly above the melting point and extending to about 950 K. These measurements are motivated by the search for a transparent substance, the Prandtl number Pr of which approaches or is even less than unity, and which shows a stable Marangoni effect with respect to potential contamination of the melt. Such a combination of material properties is mandatory in the attempt of physical modeling of laser welding processes where optical access to the bulk of the fluid is needed to measure the flow field. In an extension to these basic studies, the electrical conductivity and the influence of the admixture of other iodides on Pr was also studied.