As a promising alternative to conventional plastics, bioplastics are increasingly being used in the packaging sector. In addition to thermal and mechanical recycling, bioplastics offer an additional waste management option in the form of organic recycling. However, operators of composting plants are very critical of the increasing substitution of packaging, as in practice the rotting times are often much shorter than the twelve weeks required by EN 13432. This often leads to incomplete degradation of the packaging, which can have negative effects on the quality and marketability of the compost. The aim of this thesis is to develop a test method for determining and quantifying the complete biodegradability of plastics, to implement it at the Chair of Materials Science and Testing of Polymers and to proof its functionality. The setup of the test stand should also have the possibility to examine changes in the materials (chemical composition, degree of crystallisation) more closely during the composting process. For this purpose, additional composting vessels for accompanying measurements (DSC, FTIR) were implemented in the test stand. In the present thesis, the basic functionality of the specially manufactured test stand (based on EN ISO 14855-2:2018) was demonstrated by a test run with PLA as sample material. However, the boundary conditions according to the standard could not be fully met. As a result, the test was terminated after the minimum duration of 45 days specified in the standard. The reasons for the invalid result could be traced back to leaks and the formation of condensation in the test stand. These can be optimised by simple measures. The results of the accompanying measurements show a clear change in the crystal structure with increasing test duration. In the course of the present work, a test stand was developed to determine and quantify the complete biodegradability. Due to the additional modifications deviating from the standard, the set-up can and will contribute to a better understanding of the composting process of plastics in the future.