Li3.25Ge0.25P0.75S4 solid electrolyte thin films were fabricated by pulsed laser deposition (PLD) method at room temperature. The ionic conductivity of the thin film is 1.7 x 10(-4) S cm(-1) at 25 degrees C which is about one-fifth of the conductivity of the bulk target material (0.9 x 10(-3) S cm(-1)). The decrement of the conductivity is attributed to the increase of Li content from 3.2 in the target to 3.6 in the thin film, which reduces the number of the lithium vacancy in the structure of the thio-LISICON. (c) 2005 Elsevier B.V. All rights reserved.