The kinetics of the reaction of 2-chloro-3-nitropyridine (ortho-like) and 2-chloro-5-nitropyridine (para-like) with a series of aryloxide ions were studied in methanol at different temperatures. Plots of Delta H-not equal versus Delta S-not equal for both reactions gave good straight lines with isokinetic temperatures of 168 and 195 degrees C. Good linear relationships were obtained from the plots of log k(2) against sigma degrees values with relatively large negative rho values indicating the formation of Meisenheimer sigma-complex intermediates. Plots of log k(2) against pK(a) values gave good straight lines indicating that the reactions show an appreciable degree of bond formation in the transition state. An addition-elimination mechanism is suggested. Copyright (C) 1999 John Wiley & Sons, Ltd.