This project is set in a context of raising awareness concerning the accumulation of plastics in oceans. As opposed to the marine environment, there is a real gap of knowledge on microplastics pollution in freshwaters. In this project, the Lake Geneva environment is investigated, concentrating on the Venoge River, the lake water surface, and the “déversoir du Capelard” – a storm overflow in Lausanne. In order to get a rapid and complete method to characterize microplastics in the Lake Geneva environment, some polymer analysis tools are suggested and tested. The goals of the study are to identify the plastic debris and to characterize the oxidation state of five different polyethylene samples. The Fourier Transform Spectroscopy appears to be an acceptable solution despite some limits. DSC would require some more researches and microscopy needs a long analysis time for little information.