Ideal growth parameters for obtaining large transparent crystals of NH4Cl and NH4Br by vapor‐phase technique are described. The electrical conductivity of such cystals and crystals grown from solution are reported. In pure NH4Cl crystals two regions with slopes 1.26 and 0.8 eV are obtained in the log&sgr;Tvs 1/Tplot. In impurity‐doped NH4Cl crystals a third region with slope 1.04 eV is also observed. In pure NH4Br crystals two regions with slopes 1.06 and 0.66 eV are obtained.