Deflection of a cold supersonic beam of Ba-... FCH3 molecules has been observed when these molecules interact with both a static and a resonant oscillating electric field. The experimental observed deflection is about 0.2 degrees when the employed resonant frequency between the two Stark levels of the FCH3 partner is 7.27 MHz. This deflection angle is five orders of magnitude higher than the value one would expect from the FCH3 dipole moment and the employed RF field gradient. This new phenomenon suggests the possibility of a significant translational motion perpendicular to the beam axis which is induced by the resonant RF electric field on the cold and high density supersonic beam. (c) 2005 Elsevier B.V. All rights reserved.