Abstract: Binuclear manganese complex[（Me3TACN）2Mn2（μ-O）（μ-CH3CO2）] [PF6]2.1H2O（MnAcL） and iron complex[（Me3TACN）2Fe2（μ-O）（μ-CH3CO2） 2] [PF6]2.1H2O（FeAcL） of 1,4,7-trimethyl-1,4,7-triazacyclononane containing carboxylato-bridge were synthesized and characterized by FTIR，elemental analysis (EA) and TGA. Low temperature bleaching of cotton knitted fabric with MnAcL and FeAcL as catalyst for H2O2 and effect of key bleaching variables on bleaching performance were investigated in detail. The conditions were optimized as follows: 30% H2O2 10 g/L，complex MnAcL 10 μmol/L （FeAcL 15 μmol/L）， penetrating agent 1 g/L， stabilizer DTA 1 g/L， pH=10；liquor to goods ratio of 20:1，and the process was carried out at 70 ℃ for 60 min. The fabric bleached with MnAcL and FeAcL achieves the whiteness index to 82.3% and 65.7%，and the bursting strength retention is 95.5% and 96.9%，respectively. The whiteness index and wettability of the fabric bleached with MnAcL at low temperature were comparable with those of fabric bleached with the conventional high temperature technique. The bursting strength retention is much better for the fabric bleached at low temperature.

Key words: metal complex, catalyst, low temperature bleaching, hydrogen peroxide, cotton fiber, knitted fabric