Marangoni convection, driven by an interfacial instability due to a surface tension gradient, has become a significant problem in the crystal growth on the ground or in a microgravity environment, To suppress and control the convection is important for material processing. Especially in the crystal growth by liquid encapsulated czochralski or liquid encapsulated floating zone technique, in which the melt is encapsulated with an immiscible medium, Marangoni convection can occur on the liquid-liquid interface and on the gas-liquid free surface. In the present paper, experiments were carried out with a double liquid layer of silicone oil and fluorinert both in an open-boat system and in an enclosed system. Flow in a cavity subject to a horizontal temperature gradient was observed. An interactive flow near the interface was measured by using particle image velocimetry technique. The measured flow field seemed to agree sufficiently with the numerical prediction. (C) 2002 Elsevier Science B.V. All rights reserved.