This paper describes the optical characterization of electrohydrodynamic @HD) fields in the liquid dielectrics subjected AC high voltage. The velocity fields are obtained by a particle image velocimetry ( I " . The EHD fields are formed in lOcSt silicon oil and ethanol with different dielectric constant. The PIV requires illuminated tracer particles for the fluid flow visualization. For the requirement, the particles of aluminum powder with good condudivity and polyethylene pow& with high resistivity are suspended into the liquids and are not related eleclrification because of the AC electric fields. From a viewpoint of EHD flow visualization, the main purpose of this study is velocity measurements of the tracer particles moved by electrostriction in the fields. The PIV applied to the measurements gives us an interesting experimental result of velocity fields for the EHD phenomena.