Ohmic contacts under ambient conditions and at a low current‐density level may become blocking at a lower temperature and/or a higher current density. By observing the temperature dependence of the applied voltage across the sample for the two polarities under the constant‐current condition, the temperature dependence of the bulk and that of the barrier, if any, can be separated. The detection of the barrier, if the presence of the latter is relevant within the range of experimental interest, is easy and unequivocal. The technique is suggested for device physics studies in which the barrier may play a dominant role but nevertheless might escape detection under usual testing procedures. The method is applicable to the higher barrier‐height values as well as low. It also allows a simple study of the semiconductor effective mass through the determination of the Richardson constant.