The measured alternating current (ac) electrical conductivity of lead nitrate [Pb(NO3)(2)] crystals in the frequency range 20-10(6) Hz at temperature varying from 200 to 320 K shows anomalous temperature dependence, having meta-stability in the temperature range from 240 to 300 K. The dynamic properties have been extracted from these ac electrical data. The frequency exponents derived from the power law of the conductivity exhibit a singularity in this temperature variation range. A critical slowing down has been observed at temperatures near 275 K. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.