Deuterium isotope effects and activation parameters have been measured for the rate constants k23 and k32 in the reaction [formula omitted] where Ln3+ and An- represent the 3+ lanthanide and the anthranilate (o-aminobenzoate) ions. The kinetics of several other selected lanthanide-ligand systems have been partially examined. Possible interpretations of the results in terms of the solvation of the 3 + lanthanide are discussed. The kinetic experiments were carried out using temperature-jump relaxation techniques. © 1969, American Chemical Society. All rights reserved.