A method has been developed for heating the electrons in a thermally generated alkali plasma by the resonant absorption of electromagnetic waves at the electron‐cyclotron frequency. The electron temperature was increased from 0.2 eV to ∼1.0 eV with the application of ∼1 W of power at a frequency of 10 kMHz. Excellent consistency has been found between diamagnetic measurements of plasma pressure, microwave determinations of plasma density, and double‐probe determinations of temperature. The observed temperature increases were in quantitative agreement with computations which consider the heat loss by thermal conduction.