Figure of merit along with low cost and easy availability are considered the important parameters of a thermoelectric material for its suitability and efficiency. This paper reports figure of merit for some common thermocouples as a function of thermal and electrical conductivity of thermoelectric materials in the high temperature range. The five different thermocouples are studied in normal mode (without any applied electric or magnetic field) for the generation of thermo emf and then the figure of merit is calculated. Finally, theoretical and experimental results are compared in the temperature range from 300-630 K.