As of 2021, the superconductor with the highest transition temperature at ambient pressure was the cuprate of mercury, barium, and calcium, at around 133 K. Other superconductors have higher recorded transition temperaturesfor example lanthanum superhydride at 250 K, but these only occur at high pressure.

In 2023 a study reported superconductivity at room temperature and ambient pressure in highly oriented pyrolytic graphite with dense