Solid-Pb-filled ZnO nanotubes are synthesized and tested for use as nanothermometers. The expansion of the filling with increasing temperature (see figure) - or the corresponding changes in capacitance - can be measured and related to temperature. The advantages of this nanothermometer are extremely low fabrication costs, superior reliability, and lower demands on structural integrity of the outer shell compared to nanothermometers based on liquid fillings.