Measurement of microwave-power handling capability, performed on high-temperature superconducting HgBa2CaCu2O6+δ (Hg-1212) microstrip lines, was carried out at a microwave frequency of 1 GHz and temperatures ranging from 77 to 120 K. These samples were prepared using a different route in which direct patterning on Hg-1212 was avoided to minimize their moisture exposure. Microwave input power was swept to high levels to drive the samples from a linear (less dissipative) state into nonlinear (more dissipative) state. Critical input power (Pc) was determined to be the crossover between the two states. The Pc values observed for Hg-1212 microstrip lines were 29.3, 25.8, 23, and 16 dBm at 80, 90, 100, and 110 K, respectively. These Pc values, comparable with the best obtained so far on other superconductors at lower temperatures, are orders of magnitude better at 100 K or higher, suggesting that Hg-1212 is promising for microwave devices and circuits operating above 100 K or higher temperatures. © 2001 American Institute of Physics.