The correlation between the thermal electron mobility, μe, the radiation-induced free-ion yield Gfi at zero applied electric field, and the most probable thermalization distance b of secondary electrons, is examined for 52 different pure non-polar dielectric liquids for which data have been reported in the literature. It is shown that, in liquids for which μe > 10−1 cm2 V−1 s−1, the variation of Gfi with μe is well represented by a relation of the type [Formula: see text] where n ≈ 0.31. The connection between Gfi and μe can be described through the product εsb, where εs is the static dielectric constant of the intervening liquid. In particular, 1/εsb is shown to correlate with both μe and Gfi. Analysis of these correlations allows us to estimate an upper limit of μe that can be attained in a room-temperature dielectric liquid, information of utmost importance from the point of view of application to liquid ionization detectors.