In this paper, we present a performance evaluation of the RF-DC transfer difference for a calorimetric thermal voltage converter (CTVC) designed by the National Research Council of Canada (NRC) at frequencies up to 1 GHz. In the first part of this paper, we describe a bilateral comparison of the RF-DC difference standards between the NRC and the National Metrology Centre of the Agency for Science, Technology and Research of Singapore, in the frequency band from 1 kHz to 100 MHz. A good agreement is observed between the two laboratories using the CTVC as a traveling standard. In the second part of this paper, we evaluate the performance of the CTVC at higher frequencies up to 1 GHz. In this part, RF-DC difference of the CTVC is mathematically modeled and experimentally evaluated in terms of the calibration factor of a thermistor mount and the reflection coefficients at its type-N input connector.Index Terms-AC-DC difference, calorimetric thermal voltage converter (CTVC), mathematical modeling, RF-DC difference.