Mathematical modeling of drug release is a powerful tool that has received wide attention due to its capability of giving insights in all phases of the development of new drugs and/or carriers. In particular, this technique can be applied from the basic theoretical studies, allowing for a deep knowledge of the mechanisms involved, to the industrial stage, where it can provide valuable sensibility about processing parameters. In this sense, studies for verification of models based on available experimental data are necessary. In this study, models based on Fick's law for mass transport were applied to a system of composite PHB/ketoprofen microparticles coated with chitosan cross-linked and uncross-linked with genipin. Model fitting showed good agreement with experimental data, especially for the case of cross-linked microparticles.