Evaporation-induced Benard convection in a thin liquid layer is found to occur in experimentally and theoretically as a separate mechanism from Rayleigh-Benard and Marangon-Benard types of convection. The phenomenon is induced by evaporation at the liquid surface, irrespective of the liquid layer bottom being heated or adiabatic. The mechanism is theoretically investigated by numerically solving the two-dimensional governing equations through discretization by means of a finite difference technique. Experimentally, cellular flow patterns are disclosed by means of a tracer method, and the temperature-time history is monitored in the liquid layer using thermocouple measurements. It is found that evaporation at the free surface of a thin liquid layer results in a negative temperature gradient in the upper stratum, in which cellular convection occurs irrespective of zero temperature gradient prevailing in the remaining lower stratum. In other words, a thin liquid layer having an evaporating surface forms two strata: heat convection with fluid motion in the upper stratum, and insulation in the lower stationary one. Copyright (C) 2002 John Wiley Sons, Ltd.