Flexible transparent clay films with heat resistant and high gas-barrier properties are fabricated by using a simple casting procedure. The properties are as follows, lower than 0.1 cm(3) 20 mu m m(-2) day(-1) atm(-1) for oxygen permeability, over 90 % total visible-light transmittance, and heat durability up to 350 degrees C. The figure shows the transparency of the film before and after heat treatment at 350 degrees C for one hour.