The molecular mobility of a LC side-chain polymethacrylate (PM6) was carried out by dielectric spectroscopy and by thermally stimulated discharge current (TSDC) methods. Six relaxation processes gamma(2), gamma(1), beta, beta(1), alpha, and delta at successively increasing temperatures were observed in PM-6. For each of them, a molecular interpretation was proposed. There is a good correlation between the peak temperature positions obtained from the global TSDC spectrum at an equivalent frequency and those obtained from the dielectric method. The TSDC thermal windowing experiments for PM-6 show the high ability to resolve the overlapping processes at low temperatures. Dielectric and TSDC methods giving different details of the observed relaxation processes, allow us to create the overall picture of molecular mobility in the system under investigation. These two methods revealing the differences and similarities of them obtained results could be considered as complementary to each other.