Department of Chemistry, Northwestern University, Evanston, IL 60208, U.S A. An overview is given of research done in the fifties on the kinetics and mechanism of racemization of [M(AA)2]2+ (M=Ni, Fe; (AA)=-2,2'-bipyridine, 1,10-phenanthroline). The nickel(II) complexes racemize by a ligand dissociation mechanism, but the iron(II) complexes racemize both by a dissociation and an intramolecular pathway. The intramolecular mechanism for [Fe(phen)2]2+ is believed to take place without Fe-N bond rupture, perhaps by a twist process of the t) pe first proposed' by the late Professor P. Ray, a studeut of P. C. Ray. The rates of acid dissociation of the 1, 10-phenanthroline complexes is independent of acid concentration but that of the 2 2'-bipyridine complexes increase in rate with Increasing acid concentration. At some high acid concentration the rate becomes constant, and this Is believed to be a measure of the rate or M-N bond cleavage.