The general theory of Torrey for magnetic relaxation by isotropic translational diffusion has been applied to investigations of nuclear and electronic relaxation in liquids. The theory leads to a general correlation time (d distance of closest approach of interacting spins, mean square flight path. D diffusion constant). It could be shown that the theoretical model fits the experimental data obtained in organic solutions of free radicals. The correlation times of dimethoxyethane and toluene exhibit activation energies of 3.0 and 3.1 keal/mole respectively at high temperature. Dimethoxyethane corresponds to the limiting case of the random flight theory where « d2, whereas Tn toluene ≈ d2 is obtained.