The particle velocities in a 3-wire electrostatic precipitator were measured by the Phase-Doppler technique. The drift velocities of the seeding aerosols showed much larger values than expected based on their estimated charge, which indicated the presence of ionic winds. The significant gradients of the aerosol concentration led to increased drift velocities. Drift velocities of the water droplets increased linearly with droplet size and the data allowed an estimation of the combination of ionic wind and turbulent drift velocities.