Photoconductive (PC) and photoelectromagnetic (PEM) effects have been observed inp‐type InSb single crystals of high purity at 77°K (extrinsic range) and 301°K (intrinsic range). Because of the large electron mobilities in InSb, and because the variation of the PEM response with magnetic field was found to be strongly dependent on surface treatment, it was necessary to develop a new theoretical model to describe the PEM effect, permitting the evaluation of bulk lifetime and both electron and hole mobilities. In addition, the model affords an interpretation of Hall and magnetoresistance effects in intrinsic InSb. When the PEM effect is analyzed using impurity or thermal scattering, assuming Boltzmann statistics, the result does not fit the data so well as the simple model presented here.