Abstract In order to understand the mechanism of the ionic conduetivity enhancement in LiCl (or LiI) containing dispersed second-phase particles (DSPP), we have performed 7Li NMR investigations on both line width and spin-lattice relaxation time (T1) at 35 MHz in temperature range of 173-483 K. An additional peak was observed to overlap the resonance absorption line. The signal-to-noise ratio was obviously increased while T1 decreased. The profile of this peak changes with type and content of DSPP and temperature. It is concluded that the ionic eonductivity enhancement and the appearing of the additional peak are both given rise by the DSPP of submicron size. The high conduction in the space charge region near the interface between LiCl and DSPP is suggested as a possible mechanism for the ionic conductivity enhancement and the appearing of the additional peak.