The treatment of aromatic aldehydes with ammonia and hypophosphorus acid gave novel C(2)-symmetric N,N-bis(phosphinomethyl)amines as a new class of 1-aminophosphinic acid compounds. Complexation properties of N,N-bis(phosphinomethyl)amines with transition metals such as Co(2+), Ni(2+), Zn(2+), Cu(2+), and Cd(2+) and lanthanide ions La(3+) and Gd(3+) were studied in aqueous solution by the pH-potentiometric method. Dissociation constants (pK) of the compound were determined by the pH-potentiometric technique. The complexation studies with compound dl-2a showed the best fit of the titration curves were obtained when the ligand metal stoichiometric ratio was 1:1 and 2:1.