An accurate temperature measurement of the core in carbothermal reduction processes, such as boron and silicon carbide manufacturing processes, is not only important from product quality viewpoint but also quite a challenging task. The core temperature in these processes ranges 2200 to 3000 K. In this study, a device has been designed to measure the core temperature. Much attention has been paid towards the accuracy of measured temperatures as this is missing in all previous studies which are mostly 7-8 decades old. The effect of relative emissivity of the target material on temperature has been studied carefully. The effect of purging gas flow rate in the measuring device on measured temperature has also been quantified along with the effect of measuring block thickness which is in contact with the core (electrode). It is found that relative emissivity of the target material and measuring block thickness has pronounced effect on temperature measurement. (C) 2008 Elsevier B.V. All rights reserved.