Abstract: A technique for measuring the concentration of combustible components of a gas mixture such as air by means of a catalytic bridge. The mixture to be analyzed is introduced into a closed chamber in which the catalytic portions of the bridge are located. After the bridge is electrically excited to heat the catalytic portions, the changes in the output bridge voltage resulting from burning of the gas by at the catalytic bridge element are measured over a prescribed interval to yield an indication proportional to the combustible component concentration. The prescribed interval is arranged to start after at least enough time has elapsed following the commencement of the electrical excitation of the bridge for the bridge to come to equilibrium under zero concentration conditions.