Electronic Journal: Physical and Chemical Kinetics in Gas Dynamics. 2008. - T.. 6 - s. 16-21. A brief overview of chemical sensors. Their classification is given, the principles of operation of some sensors and the scope of their application are described. Special attention is paid to electrochemical sensors, biosensors and optical chemical sensors. The fundamental phenomena underlying the action of optical chemical sensors . are considered The principle of operation of the integrated-optical chemical sensor of absorption type. is described Potential applications of integrated-optical sensors, for example, in the chemical industry, microelectronic industry, ecology and medicine, were emphasized.