A new scheme to describe ionized monatomic gases with multiple kinds of ions is suggested. The conservation equations of the momentum, energy, numbers of nuclei and electrons (both bound and free) are derived. Local equilibrium flows of dissociated ionized oxygen are considered. Temperature dependence of oxygen atoms, ions and free electrons concentrations is calculated for the case when the initial density of oxygen atoms is equal to the Loschmidt’s number. The dependence of pressure on temperature is also emphasized.