In this study, a theoretical and experimental analysis are presented on the complete interface problem between a solar concentration system and a high temperature thermochemical process in a rotary kiln. Radiative, conductive and convective heat transfer between a freeboard of burden solid, the interior surfaces of a rotary kiln and the exterior medium of a kiln are analysed. The kiln operates in a cascade state and the hypothesis of well mixing is considered. The radiation flux density distribution in the receiver kiln, the solar and infrared bands radiation exchange and the useful heat transfer are all considered in the analysis. The parameters such as temperature distribution in the kiln, as well as thermal efficiency are determinated in function for mass flow rate of granular solids, the inclination angle and rotational velocity of the kiln and for incoming concentrated solar radiation. The heating of inert sand was chosen for experimental study conceived and realized in the 1000 kW thermal solar furnace system at Odeillo. Comparison between theoretical and experimental results is good though the insufficient investigation for variation of heat transfer coefficient with temperature.