A series of long chain fatty acids is prepared with alternating blocks of fluorocarbon and hydrocarbon. This hybrid construction provides three domains (fluorous, hydrocarbon, hydrophilic) on the same molecule. The ability of the monocarboxylic acids to form monolayers on water is explored and, in selected cases, X-ray structure analysis of the dicarboxylic acids provides information on the conformation and solid state organisation of these molecules. The hybrid molecules display surface behaviour and show packing distances which are intermediate between alkyl and perfluoroalkyl chains. (c) 2005 Elsevier B.V. All rights reserved.