The flow of a highly rarefied gas in a parallel‐plate channel and the transfer of heat owing to simulataneous thermal radiation and free‐molecule convection has been investigated analytically. The analysis is facilitated by analogies which exist between the processes. The mass throughflow has been determined as a function of the temperatures and pressures of the system and of the channel dimensions. The heat transfer analysis is first carried out in general and then specialized to the boundary conditions of uniform wall temperature, uniform wall heat flux, and the adiabatic wall. It was found that at temperature levels corresponding to room temperature and above, the results for the combined convective‐radiative transport differed little from those for a purely radiative transport.