In several plasma thrusters, perpendicular electric and magnetic fields accelerate the plasma. The DC applied electric field requires the use of electrodes that draw current. The current drawn results in erosion, and there is interest in electrode-less plasma thrusters. We examine theoretically the motion of a charged particle in perpendicular oscillating electric and magnetic fields. For simplicity, the electric and magnetic field are given and are assumed to be uniform in space. It is found that when the phase between the fields is zero, as in propagating wave, the particle gains an average constant velocity. However, If the phase is pi/2, as in a reflected wave, the amplitude of the particle oscillation velocity increases in time in the electric field direction. Moreover, the particle accelerates in the direction perpendicular to the fields. When the frequency is larger than the cyclotron frequency associated with the oscillating magnetic field, the acceleration in the perpendicular direction is dominant.