Lithium ion diffusion coefficient measurements were carried out on LISICON (Li(3.5)Zn(0.25)GcO(4)) and on a zinc-rich analogue (ZRA; Li3Zn0.5GeO4) using neutron radiography (NR). Smearing (LiNO3)-Li-6-saturated solution on a surface of a rectangle-shaped sample consisting of Li-7 and subsequent annealing enabled the relatively low temperature diffusion experiment down to 300 degreesC. The measured isotope concentration profiles agreed well with the diffusion model from the surface into the semi-infinite media, and the diffusion coefficients can be obtained for both LISICON and ZRA in the temperature range between 300 and 500 degreesC. The diffusion coefficient of LISICON is essentially larger than that of ZRA, while similar a Haven ratio was found. This indicated that the larger conductivity in LISICON was mainly caused by the higher lithium ion mobility and not by the difference of diffusion path. (C) 2003 Elsevier B.V. All rights reserved.