We describe two diagnostic methods for measuring the velocity components of mildly relativistic, high current electron beams. The first involves a measurement of the radial electrostatic potential and of the beam current and yields the time resolved, spatially averaged axial beam velocityv∥. The second requires a measurement of the beam cyclotron wavelength in the guiding magnetic field and yields a spatially averaged product &ggr;v∥, where &ggr;=(1−v2⊥/c2−v2⊥/c2)−1/2andv⊥is the transverse beam velocity. By combining the two techniques we obtainv∥andv⊥for a 0.4–1.2 MV electron beam carrying a current of 1–2 kA.