The electrical conductivity of solutions of cesium in ammonia, methylamine, and their mixtures has been measured as a function of composition and temperature. The effect of the molecular size of solvents on the electrical conductivity has been investigated. The Knight shifts and the line widths of Cs-133 in cesium-ammonia and mixed solvent solutions have been measured as a function of temperature and metal concentration. A marked change of electron dynamics in these systems around the metal-nonmetal transition region has been observed, and the properties of excess electrons in these systems have been examined.