A gas Cˇerenkov counter is described which is suitable for charged‐particle detection in the Bev region (&bgr; from 0.980 to 0.999). Calibrations of the counting efficiency are included along with a table of indices of refraction of suitable gases. The use of this counter as a threshold detector to discriminate between elastic and inelastic pions in the momentum range of 1 to 2 Bev/c is discussed. Use of the counter to differentiate between charged particles of different mass in a momentum‐analyzed beam is also considered.