The methanolyses of three neutral organophosphorus esters, namely paraoxon (O,O-diethyl O-p-nitrophenyl phosphate (12), O-ethyl O-p-nitrophenyl methylphosphonate (13), O-ethyl S-3,5-dichlorophenyl methylphosphonothioate (14, a model for VX), and an anionic phosphonate ester, O-hydrogen S-3,5-dichlorophenyl methylphosphonothioate (15, a model for a toxic hydrolytic decomposition product of VX known as EA2192)), promoted by solid supported lanthanide ion catalysts (La3+, Sm3+, Eu3+, Yb3+) were investigated at 25 degrees C under pH controlled conditions in methanol. The supports were derived from commercially available chlorobenzylated silica and chloromethylated polystyrene functionalized with two chelating ligands, iminodiacetic acid (IDA) and ethylenediamine-N,N '-diacetic acid (EDDA), followed by exposure to Ln(3+) ions. The catalysts showed good activity at two investigated (s)(s)pH values of 8.8 and 11 (in methanol). Despite the fact that the methoxide promoted reactions for the four substrates span a range of similar to 20 000-fold, the apparent second order rate constants (k(2)(app)) for methanolysis of these promoted by the solid supported lanthanide catalysts were rather insensitive to the nature of the support (Si or polystyrene), Ln(3+) ion, substrate, and (s)(s)pH. The Yb3+ complex of IDA on silica (Si/IDA/Yb) gave the highest k(2)(app) values of 6.6 and 14.4 M-1 s(-1) for 12 and 13, 48.8 M-1 s(-1) for 14, and 2.6 M-1 s(-1) for 15 at (s)(s)pH 11. The acceleration of cleavage of 13 at (s)(s)pH 8.8 by the Si/IDA/Yb catalyst at an apparent concentration of 4.8 mM (50 mg suspended in 2.5 mL of methanol) is about 8.5 x 10(5) faster than the methoxide reaction at that.:pH. The acceleration of the cleavage of 14 and 15 by 50 mg of Si/IDA/Yb at (s)(s)pH 11 is 6.3 x 10(5)- and 5 x 10(8)-fold relative to the methoxide promoted reaction at that (s)(s)pH. The matrixes containing the smaller lanthanide ions like Eu and Yb could be recycled at least eight times without loss of activity.