A flame of atomic hydrogen has been investigated for the purpose of testing its possibilities regarding the investigation of thermic emission and absorption of radiation by gases ( Β§ I). The apparatus ( Β§ 2) is sketched in fig. 1. The optical arrangement for the measurement of temperatures by means of line reversal is given in fig. 2 and described in Β§ 3. The general appearance and the flame properties are described in Β§ 4, where amongst other things it is pointed out that the discharge is periodic. The distribution of the temperature in a horizontal section of the flame ( Β§ 5) is represented in fig. 3, while fig. 4 and the table give the vertical course of the temperature as well as its dependance on the arc current etc. Simultaneous reversal measurement of several spectral lines was found to lead to the same reversal temperatures ( Β§ 7), the conclusion being that the population of the respective upper levels complies with the B o 1 t zm a n n formula. From the combined results we may conclude that the flame of atomic hydrogen can be used with advantage for the determination of transition probabilities of spectral lines with excitation energy 6 e V. For a number of details, see the original publication 1).