Abstract: This paper reports the solution chemistry behavior of N,N' ,N"-tris (2, 3-dihydroxy-5-sulfoben-zoyl)-1,5,10-triazadecane(3, 4-LICAMS)with U( IV )and U( VI) using potentiometric titration and spectrophotometric titration methods.The titration curve of the free tricatechol ligand, 3,4-LICAMS shows an inflection at m = 3 (m is moles base added per mole ligand or metal ion) and pH=9. 2. This represents the dissociation of the three phenolic hydrogens ortho to the carbonyl. The ligand protonation constants are calculated by nonlinear least square BETA programme, CDC CYBER 170/825 computer. The electron absorption spectra of benzen,catechol and 3,4-LICAMS are compared.At high pH the six phenolic oxygens derived from catecholate group in 3,4-LICAMS form a high-spin octahedral complex around U(IV) or U(VI). The titration curve of one to one 3,4-LICAMS to U( IV ) shows slow solution equilibrium at m = 4, pH = 3. 8 and a break at m = 5, pH = 5. 9. This curve is lower than the curve of free ligand (3, 4-LICAMS). The precipitation of (U(OH)4) x is not produced even at pH= 10. 5. It indicates that 3, 4-LICAMS can strongly combine with U( IV ) . The electron absorption spectra of the system of one to one 3,4-LICAMS to U( IV ) are shifted to long wave side with the increase of pH. All of the spectra coincide in △λ= 250-350 nm at pH = 3. 8, then separate from each other at pH= 3. 8 (at pH= 5. 8 for free ligand, 3, 4-LICAMS) and finally coincide again at pH=8. 78-10. 2. There are two isosbestic points at 374 and 485nm,pH=5. 96-9. 31,corresponding to the equilibrium, (UL)5- +H + (UHL)4-. The formation constants of (UL)5-, (UHL)4-,(UH2L)3-are calculated to be lgβ110 =43. 40,lgβ111 =46. 51 and lgβ112 =50. 23.3,4-LICAMS can strongly coordinate with U( VI) too,but the stability of complexes are less than that of U (IV ) . The titration curve of ratio 1:1 of 3,4-LICAMS to U( VI ) shows a slight break at m = 3 pH=5. 01 and a big break at m =5, pH = 8. 70. The spectra are separated from each other at pH = 4. 53 in △λ=250-350nm. There is a isosbestic point at 494nm,pH=5. 21-6. 46,corresponding to the equilibrium (UO2H2L)5-+H + (UO2H3L)4-. The spectra of f-f electron transition of UO 22+ at 380-482nm is strongly influenced by reaction conditions. The formation constants of (UO2L)7-, (UO2HL)6-,(UO2H2L)5-,(UO2H3L)4- and (UO2H4L)3- are as follows:lgβ110 =39. 74,lgβ111 =42. 98,lgβ112 =42. 26,lgβ113 =49. 62 and lgβ114 =53. 25.