The formation of ionic complex at the air/water nit6rface could diminish theeleCtrostatic repulsion among the hydrophilic anions of amphiphiles and increasethe stability and transferability of the monolayer. The results of X-- ray distraCtionindicated that Y-type LB films of 2C14SNa were transferred to the polystyrenesubstrates either on pure water or on PEI solution. The difference of the repetitionperiod of these LB films was about 0.30 tim.