We report detection in liquid He cooled n-Hg1-xCdxCdxTe at wavelengths between 140 and 1200 µm. With the mole fraction, x, of Cd <0.4m the alloy behaves as an electron bolometer with similar detectivity, but much improved bandwidth, compared with n-InSb. With x > 0.48 the detection process is extrinsic photoconductivity with an energy gap of a few meV. Lattice absorption severely limits detection in the wavelength range 220-340 µm. © 1985.