The dynamical equations for each component of a partially ionized monatomic gas are presented in two forms. These formulations should be most useful in analyzing the effects of ionization in such nonequilibrium regions as plasma oscillation and boundary layers. Using a perturbed Maxwellian distribution to evaluate the collision integrals, the appropriate transfer equations for the multi-component gas have been given. These transfer equations simplify greatly when the gas is assumed to be very lightly ionized and are reduced to the equations of a single-fluidwith-conduction model. Secondly, the equations for a three-fluid model are derived. In this model the properties of each species are defined in terms of its own motion, and not in terms of the total mass motion as in the one-fluid model. This model provides a useful physical interpretation of Joule heating effects. (Author).

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