The temperature profiles in wall-stabilized atmospheric-pressure arcs in pure argon and in argon–carbon dioxide mixtures have been obtained at currents of 5–40 A and for molar percentages of CO2 ranging from 0.9% to 25% using spectroscopic techniques. With the addition of CO2 to a pure-Ar arc, we show the formation of a core of higher temperatures with a larger gradient of the radial temperature distribution at the arc centre. These investigations show that the addition of even a few percent of CO2 to Ar has a marked effect both upon extinction of the arc according to current values and upon the temperature profiles. Few measurements have been done in Ar–CO2 mixtures in a wall-stabilized arc.