We present a modified steady-state heat flow technique, which allows measuring the thermal conductivity of films applied on a substrate. The measurement technique with the here presented setup provides an accuracy (overestimation) of 5-10% for film thickness up to 100 mu m. For thicker films a correction factor based on finite-element simulations has to be used or the geometry has to be adapted. The technique is validated with thin glass plates of known thermal conductivity. To demonstrate the application of the technique the thermal conductivity of a thin polymer film of fluorinated acrylate is determined as 0.19 +/- 0.02 W/mK. (c) 2006 Elsevier B.V. All rights reserved.