Аннотация:Measurement results of particle velocities in parametrically excited stationary waves of a two-layered liquid are presented. A horizon, on which the vertical harmonic components of the velocity are equal zero is determined. A system of slow recirculating streams is found to take place concurrently with oscillating motions of liquid particles. Optical system strictly linked to the oscillating vessel consists of two-channel differentiating circuit with frequency demultiplexing. Vertical and horizontal velocity components were measured by turns in switching on a proper modulator channel.