A model for predicting bremsstrahlung energy deposition in first-wall materials and the effect of this energy deposition on wall temperature distributions is proposed. In this model the bremsstrahlung energy spectrum is divided into a finite number of discrete energy groups, each with an overall power fraction and average wavelength. The volumetric heating effects of each of these individual groups are superimposed to obtain overall temperature distributions in first-wall configurations using rectangular and cylindrical coordinates. The proposed multigroup model is then applied to several first-wall designs and compared with existing models, notably the “surface-heating” model, which utilizes the assumption that the bremsstrahlung energy is deposited on the wall surface. It is concluded that in many designs involving advanced fuels or low-Z first-wall materials the surface-heating model over-predicts wall temperatures near the plasma side, and the multigroup model may be necessary for accurate temperature calculation.