An effective momentum transfer collision frequency for electrons in cesium plasmas has been determined from measurements of the electrical conductivity and plasma properties in a cesium arc column. The effective collison frequency was found to depend on electron temperature in the 2500 to 4500°K range and to be significantly dependent on degree of ionization for values of this parameter greater than about 3 × 10−4, indicating a contribution from electron‐ion collisions. Numerical evaluations of the velocity integral for the electrical conductivity, modified to include electron‐ion as well as electron‐atom momentum transfer collisions, have been carried out using many trial functions for the electron‐cesium atom momentum transfer cross section. The electron‐atom cross section which has given the best fit between the calculated and measured conductivity exhibits a Ramsauer‐like minimum in the 0.25‐to 0.55‐eV range of electron energy.