The large production of acidic oligosaccharides was investigated by non-enzymatic depolymerization of polygalacturonic acid (PGA) using free hydroxyl radical hydrolysis process from H2O2/copper (II) system. A large amount of oligogalacturonides (OGAs) with degrees of polymerization up to 6 were fractionated, and characterized by ESI-Q/TOF-MASS spectrometry and 1H NMR spectroscopy. This efficient production of uronic oligosaccharides from PGA constitutes an original process to produce bioactive compounds in large scale up.