In this paper, the phase diagram of the RbF-RbI system is studied by means of differential thermal analysis (DTA) firstly. The experimental data have been analysis and evaluation by using the thermodynamic calculation and the support vector machine (SVM)-atomic parameter method for the system. The results show that the phase diagram of the RbF-RbI system is of the simple eutectic type, where the eutectic is found to have the composition X(RbF) = 35 mol% (melting point approximate to 495 degrees C), and it is suggested that no solid solution form in the system. (C) 2008 Elsevier B.V. All rights reserved.