Abstract—The interaction of acetylene molecules with the (H2O)20 cluster was studied by molecular dynamics simulation. The behavior of the derivative of the chemical potential (i is the number of acetylene molecules) shows that the cluster stability is retained when no more than two C2H2 molecules add to the cluster. The system composed of (C2H2)i(H2O)20 clusters has higher values of dielectric permittivity (both real and imaginary terms) than the (H2O)20+n cluster system. The medium formed by water clusters with C2H2 molecules both absorbs and reflects IR radiation with a higher intensity as compared to a system of this type with pure water. The addition of C2H2 molecules to water clusters is also accompanied by an increase in the number of bands in an IR reflection spectrum. Adsorbed C2H2 molecules are aligned with the tangent to the water core of the cluster, thus impeding their penetration into the aggregate and, hence, decreasing the solubility of acetylene.