New correlations, based on the rough hard-sphere theory and an extensive literature database, were developed for the determination of the binary diffusion coefficients of liquid and solid solutes ion supercritical solvents. The correlations were tested to predict 107 solute-solvent systems with good results. The input data required for the correlations are the solute molecular weight, temperature, density and the solvent basic properties (molecular weight, critical volume, and critical pressure).