Broad-band dielectric and conductive spectroscopy covering a 10 mHz-10 MHz frequency range has been employed to examine both the ionic and dipolar motions in a single-non conducting copolymer of nona-oxyethylene methacrylate and alkali-metal methacrylate, P(MEO9-MAM) with M = Li, Na, and K. Analysis of the observed spectra revealed an existence of three dielectric relaxation processes associated with the dipolar motions in the methacrylate main chains (alpha) and oxyethylene side chains (beta, gamma). On the low frequency side of the alpha process an additional process alpha＇ was observed that was attributed to a local ionic fluctuation in a heterogeneous medium. Its relaxation frequency depended upon the ionic species and increased in the order of Li < Na < K in parallel with an increase of de conductivity sigma(dc). Comparing the temperature dependence of sigma(dc) and the relaxation frequencies of these processes, we conclude that the main-chain motion governs sigma(dc) through the dissociation of metal ions at low temperatures and spatial heterogeneity as well as the side-chain motion governs the ionic mobility at high temperatures. (C) 2000 Elsevier Science Ltd. All rights reserved.