The main purpose of this proposal is the theoretical investigation of structural, rotational, vibrational, and electronic properties of para-hydrogen (pH2)n, (pH2)n+carbon dioxide (CO2) and (H2O)n clusters confined in helium nanodroplets using ab initio molecular dynamics simulation techniques. Progress in technologies dealing with liquid helium makes it possible to embed not only single atoms or molecules but also whole molecular complexes of mixed content inside superfluid helium droplets. As the mutual interaction of embedded impurities is much stronger than with surrounding helium atoms, they form clusters inside of the helium nanodroplets. Helium clusters can also be exploited to search for superfluidity of other substances embedded into helium nanodroplets. Despite intensive theoretical and experimental efforts during past decades, this remarkable effect is still far from a complete understanding. Electronic spectra of the molecules and clusters in helium droplets can provide important information about structure and dynamics of the environment created by helium and predict thresholds of superfluidity phenomena. The proposed research aims to provide novel insight into structure and dynamics of substances in superfluid helium and provide a strong base for an investigations of helium and hydrogen nanodroplets doped with chromophor molecules for seeking superfluidity of helium and hydrogen clusters.