The dielectric constant eT of Cu Cl boracite changes very little with temperature above the transition point Tc, increases abruptly at Tc upon cooling, and decreases below Tc. This behavior is expected in the theory of improper ferroelectric transitions. The d.c. resistivity jumps abruptly at Tc. However, the sign of the jump is different for different samples. At 25 Deg, the a.c. resistivity decreases with increasing frequency. Unpoled samples show a.c. and d.c. resistivities 2 orders of magnitude lower than samples in the single-domain state.