A one‐dimensional theoretical model for predicting the heating of a hydrogen plasma in open confinement systems by a relativistic electron beam is presented. Direct energy transfer of beam electrons via interaction with large amplitude waves of the two‐stream instability and Ohmic dissipation of plasma return current caused by classical and anomalous resistivities are considered as power input terms. For loss terms, various atomic processes and heat conduction mechanisms are considered. In the light of observed changes in the average scattering angle of the beam inside the plasma, criteria deciding the character of beam–plasma interaction and the estimation of direct power transfer are discussed. The numerical results are presented with a reference to the results of the beam–plasma heating experiments reported in the literature. Better agreement is observed between the experiment and the present analysis.