Free-radical depolymerization with metallic catalysts has been investigated to depolymerize an exopolysaccharide (EPS), with a high molecular weight (> 10(6) g/Mol), produced by the bacterium Alteromonas macleodii subsp. fijiensis biovar deepsane. Three metals (copper, zinc and manganese) were used either alone or mixed. These metals led to the depolymerization of the high molecular weight bacterial polysaccharide with different efficiency. This study specifies some conditions required to produce, with good reproducibility and yield, EPS derivatives of reduced molecular weight ranging from 100,000 to 20,000 g/mol. The more influential parameters are specified. This is a first study to find suitable industrial conditions in the presence of these metallic catalysts. (c) 2005 Elsevier Ltd. All rights reserved.