Аннотация:The dependence of the generalized initial expansion rate of a high-current discharge channel possessing cylindrical symmetry in an unbounded dense gas on the generalized variable is determined from experimental data and dimensionality theory. Such a dependence agrees satisfactorily with the experimental data obtained by some researchers in different years. Proceeding from dimensional theory we also derive formulas for the plasma temperature and the discharge channel expansion rate with an accuracy to a numerical factor of the order of unity, which were obtained earlier within the self-similar theory of such discharges in an unbounded gas.