Modeling and experimental results are presented concerning the heat transfer and fluid flow for an argon d. c. arc plasma jet impinging normally upon a flat plate. Both laminar and turbulent flow regimes are involved in the study. Temperature- and concentration-dependent gas properties are used, and the mixing between the argon plasma jet and the ambient air is modeled by using the combined-diffusion-coefficient approach. For the case of turbulent flow, the K − ε two-equation turbulence model is employed in the modeling. The modeling results show an appreciable difference in the mixing processes for the laminar and turbulent regimes. A transient method is employed to measure the local heat flux distribution along the surface of flat plate impinged by the argon plasma jet, whereas the pressure distribution along the plate surface and the electron temperatures near the plate surface are measured by using a stationary water-cooled probe. Different gas flowrates, arc currents and plate-standoff-distances are covered in the measurements. The predicted and measured heat flux and pressure distributions can be well approximated by the Gaussian distributions. The measured electron temperatures near the cold plate are shown to be much higher than the plate temperature, implying that the near-wall boundary is in a state of highly thermodynamic non-equilibrium.