Studies of intensity‐dependent transmission of pulsed radiation of nanosecond duration at 10.6 &mgr;m very near the band gap inn‐Hg0.77Cd0.23Te at low temperatures show evidence of abrupt limiting behavior which manifests itself in no additional transmission for incident intensities exceeding approximately 200 kW/cm2atT⩽20 K. Measurement of the spectral broadening in the transmitted radiation for excitation of nanosecond duration suggest that such self‐enhanced ’’opacity’’ can be switched on in less than 500 psec. The surprisingly low observed threshold intensities are considered by examining the contribution from inelastic hot‐electron collisions to the generation of excess free carriers.