In this contribution we employ a low temperature method for the deposition of thin and highly porous layers based on ZnO nanocrystallites. The method is based on coating of a substrate with ZnO suspension and thereafter the application of quasi static pressure on the sample. A high temperature step becomes redundant and the temperature does not exceed 120 degrees C during the whole process. The porosity, the specific surface area and the pore size distribution can be influenced by the variation of the process pressure. The influence of oxygen and water vapor on the photoresponse is investigated and a model explaining the observed behavior is discussed. (C) 2011 Elsevier B.V. All rights reserved.