Improper disposal of plastics after use leads to increasing concerns due to the growth of global environmental problems such as increasing CO2 emissions, decreasing oil sources and environmental pollution resulting in the need for research and development of biodegradable materials as an alternative to conventional packaging materials. The constant depletion of natural resources caused by petroleum-based materials leads to the emergence of new biopolymer materials applicable as packaging materials. Biodegradable materials break down in the environment under the influence of microorganisms, water, oxygen and sunlight, are compostable and are produced from renewable energy sources. In addition to the positive impact on the environment, biodegradable materials are also favorable for use from an economic point of view because they are cheap, easily available and reduce the dependence of the market price of plastic on the oil industry. In this work, the application properties of the prepared biodegradable polymer mixtures of thermoplastic starch (TPS) and polylactide (PLA) without and with the addition of citric acid (LK) were analyzed. The overall identification and characterization of biodegradable TPS/PLA mixtures was carried out by FTIR - ATR spectroscopy, the morphology of polymer mixtures was monitored using scanning electron microscopy (SEM), thermal properties using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques, and permeability was also tested water vapor (PVP) and mechanical properties of prepared polymer mixtures. The results indicate an improvement in the adhesion between TPS and PLA phases with the addition of citric acid, better homogeneity in the structure and stronger compatibility of the polymer mixtures, which results in better thermal, mechanical and barrier properties of the analyzed biodegradable polymer TPS/PLA mixtures.