This work reports the encapsulation of latex particles in Al2O3-polystyrene (PS) composite films. These films were prepared from PS particles in Al2O3 dispersion at room temperature in various latex contents. Composite films were annealed at elevated temperatures in 10 min time interval above the glass transition temperature (T,,) of polystyrene. Transmitted photon intensities. I-tr were monitored after each annealing step. AFM micrographs were also used to observe the physical changes of the composite films during annealing. It was observed that latex particles are encapsulated above a critical Al2O3 content of 33 wt% which corresponds to the critical occupation probability of p(c) = 0.33 at which the film obey the site-percolation model with a critical exponent of 0.45. Below pc it was seen that complete latex film formation process took place, where transparency of the film was increased by annealing. (c) 2005 Elsevier Inc. All rights reserved.