Research is underway into the use of nanofluids to improve the cooling of surfaces within fusion reactors that are exposed to extreme heat fluxes. Nanofluids are a mixture of liquids (typically water) with nanoparticles (<100nm) in a concentration that is usually less than 1% by volume. Nanoparticles being investigated are alumina, ceramics, and carbon nanotubes, as these are known to increase both the conductive and convective heat transfer coefficients by up to half an order of magnitude (5x), and the critical heat flux of current coolants by up to an order of magnitude (10x) for boiling heat transfer. Due to this, cooling systems that are based on nanofluids could deliver a step‐change in the power handling performance of heat exchangers and other components.