Abstract
The velocities of dislocations in crystals of pure and HCl-doped ice have been determined by synchrotron X-radiation topography. In the temperature range -28 to -55[ddot]C doping at a level which increases the dielectric relaxation rate by an order of magnitude has no such effect on the velocity of basal 60[ddot], basal screw or non-basal edge dislocations. This means that in pure or lightly doped ice the rate of reorientation of hydrogen bonds required for dislocation glide is not that typical of the bulk material.