Abstract Modern studies now favor the fact that extraterrestrial organic molecules served as an important source of biological important substances on the primitive Earth. It is presumed that these space-made organic molecules could be transported safely to the Earth surface being associated with mineral grains. It is important to test whether nucleotides synthesized in Earth orbit could be protected by lunar surface regolite. The phosphorylation of adenosine, uridine and thymidine has been studied with respect of their further transformations and degradation in presence of mineral bed. After retrieval, HPLC analysis is used to identify all the mononucleotides of certain nucleosides. It has been shown, that exposure of the investigated nucleosides as dry films in space conditions in the presence of Lunar soil increases the yield of synthesized nucleotides in 1.1 – 3.0 times as compared with the exposure of the same samples in absence of Lunar soil. To identify and evaluate the principal source of energy in open space responsible for nucleotide synthesis reaction laboratory experiments were performed. It has been shown, that vacuum ultra violet (VUV 145 nm) radiation promotes nucleotide synthesis more effectively than ultra violet (UV 254 nm) while the presence of Lunar soil increases reaction yield in 1.5 – 2.0 times. Formation of 5′-mononucleotides seemed to be the most effective reaction both in flight and in laboratory experiments. Protective action of lunar soil on synthesized nucleotides against UV radiation has been shown in open Space conditions.