The properties of potassium and sodium-potassium alloy solutions in tetrahydrofuran with dicyclohexano-24-crown-8 as a complexing agent were studied by means of K-39 and Na-23 NMR, ESR, and chromatographic methods. The metal solubility and composition of the systems as well as the temperature dependence of the T-1 and T-2 relaxation times for metal ions are described. Exchange mechanisms are proposed for both systems. The stabilities of the solutions are compared and reveal enhanced resistance of the NaK system to decomposition. The unexpected behavior of Na- as compared to that of K- is discussed in terms of equilibrium processes involving "genuine" Na- ions and Na- dissociation products.