Chemical modification of biopolymers in polyurethane synthesis allows both replacement of oil-processing products with environment-friendly components and reducing usage of non-recoverable natural resources. To obtain biodegradable polysaccharide based polyurethane networks, exopolysaccharide xanthan produced by Xanthomonas campestris bacteria was used as hydroxyl containing reagent interacting with blocked polyisocynate (PIC) that dissociates upon heating to recover free NCO-group. The developed synthesis technique offers the possibility to obtain polyglucanurethanes (PGU) in films, powders and reinforced materials. The biodegradability of the reinforced PGU was examined by introduction into the typical Ukrainian soil (chernozem) and was controlled via optical microscopy. To provide the detailed analysis of the polymer destruction processes, the PGU of various compositions were exposed to common association of soil microorganisms as well as in the medium of resistive microbial association isolated from soils polluted by chlorine-organic pesticides. Using FTIR spectroscopy and thermogravimetry analysis, the pattern of bond cleavage as well as changes in thermo-oxidative destruction were analyzed. According to the FTIR-data, in aggressive medium, mainly the degradation of glucopyranose cycles and urethane bridges occurs, while in the natural medium the intercyclic ether bonds of polysaccharide degrade. The TGA data point on significant reduction in thermal stability of degraded PGU and confirm fragmentation of the polymer.