This paper presents the modeling of an argon micro-plasma produced by microwaves (2.45 GHz) at atmospheric pressure. The study uses a one-dimensional stationary fluid-type code that solves the transport equations for electrons, positive ions Ar+ and Ar+
2, and the electron mean energy, together with Poisson's equation for the space-charge electrostatic field, Maxwell's equations for the electromagnetic excitation field and the gas thermal energy equation. The model uses a simple kinetic scheme for Ar that includes the ground state, an excited state representing the lumped 4s levels, and two ionization states associated to the atomic and the molecular ions. The ions are assumed to be in thermal equilibrium with the neutral gas, having the same temperature profile.