A new method for characterising the wetting of structured surfaces is presented. Sessile drops of a warm agarose solution were placed on test surfaces and then removed after the gelation of the agarose solution caused by the cooling of the drop. By studying the base of the sessile drops using confocal microscopy and image processing it was possible to determine the wetting mode and general appearance of the liquid-gas interface beneath the drop. The method also shows potential to measure the wetted area, and local contact angles beneath the footprint of a sessile drop. The applicability of the method was also demonstrated by its application to periodically structured photopolymer plates and surfaces covered by microsized glass spheres. (c) Koninklijke Brill NV, Leiden, 2008