Abstract: A selective chemical sensitive field-effect transistor device for use in detection and measurement of chemical properties of substances to which the device is exposed is disclosed. The chemical sensitive FET device comprises a semiconductor substrate, at least one pair of spaced apart diffusion layers formed on one surface of the semiconductor substrate and forming source and drain regions, respectively, and a double layer structure consisting of a silicon oxide layer and an electrically insulating layer overlaying the silicon oxide layer. A gate region located on a portion of the surface of the semiconductor substrate between the diffusion layers is overlaid with a chemical selective membrane adapted to interact with certain substances. A method for the manufacture of the above described FET device is also disclosed.