Abstract : Aqueous suspensions of waxy maize starch nanocrystals are obtained by acid hydrolysis of native starch granules. The first objective was to optimize the preparation of such nanocrystals using a response surface methodology. Then, their molecular structure has been studied by enzymatic analysis and their surface chemical modification has been investigated. The second objective was to use these nanocrystals in a polymer matrix. Two natural polymers have been chosen: a latex of natural rubber and thermoplastic starch. Nanocomposite films, processed by casting, have been characterized in terms of morphological, structural, barrier and mechanical properties.