Summary:

We give simple but accurate numerical fits to various two-body rates in relativistic thermal plasmas, in the temperature range kT _e ~ 50 keV--1 MeV. The processes we discuss are bremsstrahlung, Coulomb heating and electron-positron pair production and annihilation. In particular we present a fit to the thermal electron-electron bremsstrahlung spectrum which is accurate to better than 5 per cent. We also include the results of some other workers, for completeness. Our results are suitable for semi-analytic or computer modelling of hot plasmas.