Spruce Organocell lignin has been oxidized by O2 under pressure in acetic acid and in the presence of NaBr or NH4Br and Co(OAc)2 as catalyst in order to obtain chelating agents. The reaction time, O2 pressure, and the Co(OAc)2/bromide ratios were varied and the product quality was monitored by analytical pyrolysis-gas chromatography. The main pyrolysis products were phenol, guaiacol, 4-methyl-and 4-ethylguaiacol, catechol, isoeugenol, vanillin, and vanillic acid. In the oxidized lignins the moiety of demethoxylated, demethylated and oxidized guaiacyl units was increased. Vanillin and vanillic acid were used as marker for determination of the oxidation increments. The longer the reaction time and the more bromide as promoter was used the higher oxidation increments between 2 and 9 were observed. The oxidation increments correlate with the severity of oxidation. The yield of degradation products with low molecular weight was low. Bromides promote mainly the oxidation and not the depolymerisation of lignins. © 1997 Published by Elsevier Science B.V.40-41 543551Gonçalves, A.R., Schuchardt, U., Meier, D., Faix, O., Production of vanillin and vanillic acid by oxidation of Organocell lignin with molecular oxygen (1993) Proc. 3rd Brazilian Symposium on the Chemistry of Lignin and Other Wood Components, 4, pp. 253-256. , Belo Horizonte, Brazil, September 8-10Chang, H.-M., Allan, G.G., Oxidation (1971) Lignins - Occurrence, Formation, Structure, and Reactions, pp. 433-485. , K.V. Sarkanen and C.H. Ludwig (Eds.), Wiley-Interscience, New YorkCotrim, A.R., Ferraz, A., Teixeira Da Silva, F., Chelating agents through oxidation of sugar cane bagasse lignin (1995) Proc. 8th International Symposium on Wood and Pulping Chemistry, 3, pp. 313-318. , Helsinki, Finland, June 6-9Meier, D., Faix, O., Pyrolysis-gas chromatography-mass spectrometry (1992) Methods in Lignin Chemistry, pp. 177-199. , S.Y. Lin and C.W. Dence (Eds.), Springer, Berlin-Heidelberg