The hot‐wire anemometer is principally used for turbulence investigations in both subsonic and supersonic flows. Its use has been extended to the observation of transient phenomena in shock tubes. Since its sensitivity to different phenomena varies, depending upon the operating conditions, the hot wire is quite well suited for timing very weak as well as strong travelling shock waves. A triggering and timing arrangement was developed pointing to further improvement. It was found that the hot‐wire trigger is a reliable instrument under widely varying shock tube operations.