Thermal effects on direct measurements of the thrust produced by steady-state, high-power (≥ 10s of kWs) plasma thrusters using inverted-pendulum thrust stands are addressed. Three major sources of systematic error exist in the determination of thrust using an inverted-pendulum thrust stand; tare forces, thermal drifts, and thermal deflections. It is shown that thermal deflections, due to changes in the temperature of the flexures used to carry the thruster current, can be the most significant of these effects. The response of the flexural elements to changing thermal loads can produce stand displacements on the order of the expected thrust (100s of mN at thruster currents of 300-500 A). Thermal deflections were reduced by at least 80% by conducting the thruster current to the stand via mercury pots rather than the flexural elements.