The classification of the “polarity” of Porapak and Chromosorb “Century Series” porous polymer bead (PPB) stationary phases was made on the basis of the retention index values of Rohrschneider's and some of McReynolds' polarity probes (ethanol, butanol, pyridine, nitromethane, 1-nitropropane, benzene, methyl ethyl ketone and methyl propyl ketone). Except for Porapak T and Chromosorb 107 and 108, the average polarities, calculated from the sum of the ΔI values of selected probes with respect of the less polar PPB Chromosorb 106, were fairly constant during the ageing of the columns. The “polarity order” obtained from the average polarities determined with butanol, benzene, methyl propyl ketone and pyridine (at 200°C) was: Chromosorb 106, Porapak Q, Chromosorb 102, Porapak R and Chromosorb 105, Porapak N, Chromosorb 101, Porapak P, Chromosorb 103, Chromosorb 104. Increasing polarities with column ageing were shown by Chromosorb 107, Porapak T and Chromosorb 108. Linear relationships between the polarity order at low temperature, calculated by gaseous probes, and the high-temperature polarity order were found when PPBs of similar chemical composition were considered.