Theoretical models are described for calculations of charge-carrier concentrations, Fermi energy, and conduction-electron mobility as functions of x, temperature, and ionized- and neutral-defect concentrations in Hg1−xCdxTe alloys. Measurements are reported of electron concentration and electron mobility from 5–300 K for alloys with 0.17 < ˗ < 0.30. The electrical data are in reasonable agreement with theory and were analyzed to obtain estimates of donor and acceptor state concentrations. The electron inobilities are calculated in terms of a microscopic theory of electrical conduction derived from the solution of the Boltzmann equation for the perturbed steady-state electron distribution function and show that longitudinal opticalphonon and charged and neutral defect scattering are the dominant mobility-limiting mechanisms.