The characteristics of an overvoltage high-voltage nanosecond discharge in air at atmospheric pressure between polycrystalline electrodes made of a superionic conductor, silver sulfide (Ag2S), are given. In the process of microexplosions of inhomogeneities on the working surfaces of the electrodes in a strong electric field, vapors of the Ag2S compound and its dissociation products in the plasma are introduced into the interelectrode space due to the formation of ectons. This creates prerequisites for the synthesis of thin films from this material, which have the properties of superionic conductors and photovoltaic compounds and can be deposited on a dielectric substrate installed in a discharge gap. Spatial and electrical properties of nanosecond overvoltage discharges and Raman scattering spectra of synthesized thin films and their surfaces were investigated. Discharge plasma parameters were modeled in a mixture of Ag2S superionic conductor vapor and air. Numerical calculations were performed using a program that solves the Boltzmann equation for the electron energy distribution function. The transport characteristics of discharge electrons and rate constants of electronic processes were calculated depending on the values of the E/N parameter in the experimental range of 1-1000 Td of the study of discharge properties. Raman light scattering spectra of thin films synthesized from electrode erosion products in air plasma are presented.