A simple attachment for the environmental technique is presented, which can be mounted in a standard scanning electron microscope (SEM) without changes in its original structure. The main part of the unit is the intermediate vacuum and detection chamber designed in the form of a compact head, which contains a ionisation secondary electron detector and a Robinson detector. An alternative is the newly designed two-stage secondary electron detector, which offers all advantages of the Everhart-Thornley scintillator detector. The unit allows gas pressures in the order of 10 mbar in the sample chamber. It is enough for the examination of not only insulators but also a range of water-containing specimens. (C) 2003 Elsevier Science B.V. All rights reserved.