The electrical conductivity is calculated for some typical seeded gases of magnetohydrodynamic interest. The electron density is obtained using Saha's equation. A method is developed for calculating electron mobility in gas mixtures, taking account of the variation of the scattering cross section with energy. Scattering by ions is also considered. Results are presented for several gases seeded with small amounts of Cs or K in the temperature range from 2000° to 4000°K.