Divalent metal‐ion complexes of 2,9‐bis[(methyldodecylamino)methyl]‐1,10‐phenanthroline (C12Phen—MII) in neutral Brij 35 micelles catalyse the hydrolysis of various phosphate triesters, diesters and monoesters. The catalytic activity of C12Phen—MII has been compared with that of the metal‐ion complexes of its water‐soluble counterpart 2,9‐bis[(dimethyl‐amino)methyl]‐1,10‐phenanthroline (C1Phen—MII). Saturation kinetics provide evidence for preliminary formation of ligand‐MII‐phosphate ester complexes, which decay to products. The hydrolysis of diphenyl 4‐nitrophenyl phosphate (1b) coordinated to C12Phen—ZnII proceeds 8700 times faster than the hydrolysis of 1b in the absence of metallocatalyst. Kinetic studies indicate that phosphate triesters containing a metal‐ion‐binding site in close proximity to the phosphoryl bond, i.e., diphenyl 5‐nitro‐2‐pyridyl phosphate (2b) and diphenyl 5‐nitro‐8‐quinolyl phosphate (3), are hydrolysed by the same mechanism as 1b.