Abstract: The relative Complexing ability of 10 sorts of carboxylic acids with Ti(Ⅳ) at pH=1.50 was studied using chromotropic acid as metallic indicater. By treatment of the spectral absorption data with a formula derived by the author, the relative complexing ability can be calculated quantitatively as follows:Oxalic acid (100)>D-gluconic acid (8)>Citric acid(33)>Glyceric acid(16) >Lactic acid(11 ,5)>Tartaric acid (10)>Succinic acid(8.4)>Acetic acid(7)>Ma-lonic acid(6)>Malic acid(l.7).The UVspectra characteristics and the way of band formation of Ti(Ⅳ)—carboxylic and Ti( Ⅳ )-hydroxycarboxylic acid were studied and discussed.According to the magnitude of λ_max , the relative stability series of the chemical bond between the Ti( Ⅳ) and the ligands from 6 sorts of hydroxy,, carboxlic acids in the interval of pHfrom 1 to 2 was established.