The measurement of the minority carrier mobility of n-type cadmium mercury telluride using Haynes–Shockley method is described. The practical and theoretical aspects of the measurement are presented and compared with the flying light spot method. Observed pulse widths were found to be larger than expected from diffusion broadening alone, a fact which is explained by the existence of an accumulating contact in the vicinity of the minority carrier detection region. The drift velocities determined from the rate of change of delay with distance were found to be relatively insensitive to this pulse distortion. Mobilities of 180 cm2/V s for Cd0.29Hg0.71Te at 185 K and 460 cm2/V s for Cd0.22Hg0.78Te at 90 K have been observed.