Lanthanide-mediated hydrolyses of micellar beta-hydroxyhexadecyl p-nitrophenyl phosphate (3) and hexadecyl p-nitrophenyl phosphate (4), as well as of their nonmicellar analogues, beta-hydroxypropyl p-nitrophenyl phosphate (1) and ethyl p-nitrophenyl phosphate (5), were examined with the tripositive cations of La, Eu, Tb, Er, Tm, and Yb at pH 7, 37 degrees C. Micellar kinetic advantages of 4-13 were observed at 2 mM Ln(3+), due to enhanced binding of the cations to the anionic micellar substrates. Tm3+ was the most reactive cation, eliciting 10(5)-fold hydrolytic rate accelerations.