Low temperature electrical transport properties of rare earth (RE) element doped Fe2VAl Heusler alloys have been investigated. Significant improvement of thermal power S (peak values -125 to -160 μV/K) is observed compared to the pure Fe2VAl (peak value 40 μV/K). It is observed that the thermal conductivity reduced by 50%in RE doped samples. As the carrier concentration of these samples is high compared conventional semiconductors, single parabolic band model (SPB) has been used to analyze the thermoelectric data. We have estimated the values of Lorentz number, β, and maximum possible figure of merit (zTmax) by using SPB model. The experimental data corroborate well with estimated values from the model. © 2017 Author(s).