Curious light scattering occurs during continuous elevation of temperature of supercooled liquid films on metal substrates. The phenomenon is observed for ethylbenzene and some related compounds when the temperature of the sample prepared by vapor deposition on cold substrate was raised to the point a little above the glass‐transition temperature but still below the temperature where spontaneous crystallization takes place. The relaxation time of particular Fourier components of structural inhomogeneity that gives the light scattering is well related to the viscosity of the sample. Surface undulation of viscous liquid is suggested to occur being caused by the difference between the thermal‐expansion coefficients of the supercooled liquid and metal substrate. © 2004 American Institute of Physics