Abstract: A process and apparatus for continuously monitoring of concentrations of gaseous components in gas mixtures, with the exception of O.sub.2. The desired concentration values are obtained simultaneously and separately for the individual gas components, without disruption and with relatively greater accuracy, by a direct path. The concentration of the gaseous component is continuously measured with the aid of at least one electrochemical cell having at least one solid body which contains oxygen-ion-conducting material and a metal-oxide-containing electrode, and generates electrical signals which are a function of the concentration of the component. The measurement signals are electronically and automatically evaluated in a computer which converts them into concentration values. The converted values are compared with reference values of a program which has been programmed into the computer earlier.