Transport equations for mass, momentum, energy, and heat flux based on the thirteen‐momentum approximation of the Boltzmann equation are analyzed in the isobaric approximation. The left‐hand‐side terms are estimated and compared with terms representing the collisional transfer for the transient case of nonequilibrium two‐temperature discharges in monoatomic gases. A simplified form of the equations is derived and the corresponding conditions are expressed as functions of the physical properties of the plasma. The system of equations is solved for a 0.5‐A argon discharge at atmospheric pressure. The arbitrary initial distributions are allowed to relax to the equilibrium state, which is compared to previous results for a 0.4‐A free‐burning discharge in argon.