The synthesis of three new 1 ,I 0-phenanthroline derivatives is reported: 2-(N-methyldodecylamino) -methyL9-(hydroxymethyI)-l ,I 0-phenanthroline (1 ), 2-(N,N-dimethylamino)methyl-9-(hydroxymethyl) -1 ,I 0-phenanthroline (2), and 2-(N-methyldodecylamino)methyl-I ,I 0-phenanthroline (3). The esterolytic activities of the complexes 1-M" and 3-MI' in the presence of cationogenic micelles and of 2-M" in pure buffer toward the substrates p-nitrophenyl picolinate (PNPP), p-nitrophenyl octanoate (PNPO), and p-nitrophenyl dodecanoate (PNPD) have been investigated. The lipophilic ligand 1 in mixed micelles forms only 1 : 1 complexes with bivalent metal ions and the order of ligand activation is Zn" > Co" > Cd" > Ni", while its water soluble analogue 2 forms both 1 :I complexes and 2:l complexes. The order of ligand activation for 2 is also different: Co" > Nil1 z Zn" > Cd". The metallosurfactant 3, lacking the nucleophilic hydroxy group, is 25 times less active than 1-Zn! For the hydrolysis of PNPP catalysed by I-Zn", a detailed kinetic analysis is given.