A comparative kinetic study of the anaerobic digestion of vinasse and vinasse following a 2 h treatment with ozone, ozone plus UV light or ozone plus UV light in the presence of titanium dioxide was carried out. All pretreatments decreased both chemical oxygen demand (COD) and total organic content (TOC). Those using no catalyst failed to improve the specific rate of methane production during anaerobic digestion but succeeded in increasing the yield coefficient (Y-P,Y-S in ml CH4/mg TOC). Finally, the pretreatment using ozone. UV light and titanium dioxide decreased COD and TOC, and increased the yield coefficient and also the mean specific rate of anaerobic digestion (by 25%) relative to untreated vinasse. (C) 2002 Elsevier Science Ltd. All rights reserved.