The efficiency of the simultaneous use of the microbial preparation Devouroil and Eisenia foetida, the Californian Red Worm, in the process of hexadecane biodegradation in soil under laboratory conditions was shown. Qualitative changes occurring during the bioconversion process were characterized. The buildup of unsaturated triglycerides after the application of the biological preparation and "biopreparation-worm" complex was shown using NMR and IR spectroscopic techniques.