Résumé : The rates of reaction of 2‐, 3‐ and 4‐chloropyridine N‐oxides towards 1 M piperidine in methanol have been measured conductimetrically. Apparent unimolecular rate constants at 80°C are respectively 3,70.10−4, 1,04.10−7 and 1,02.10−4 sec−1. The reactivity sequence 2 > 4 >> 3 is discussed in terms of competing inductive and “built‐in solvation” effects. Copyright © 1961 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim