A study of the kinetics of the anaerobic digestion of brewery wastewater was carried out using a 1-litre, continuous-flow, completely-mixed, bioreactor operating at 35 degrees C and containing a saponite-immobilized biomass at a concentration of 6.2 g volatile suspended solids (VSS)/litre. The bioreactor worked satisfactorily in a range of hydraulic retention times from 1.2 to 10 days and eliminated more than 95% of the initial chemical oxygen demand (COD) in all instances. Guiot’s kinetic model was used to determine the macroenergetic parameters of the system, and showed it to have a yield coefficient for the biomass (Y) of 0.080 g VSS/g COD and a specific rate of substrate uptake for cell maintenance (m) of 0.045 g COD/g VSS day. The experimental results showed the rate of substrate uptake (R(s);g COD/g VSS day), correlated with the concentration of biodegradable substrate (S-b;g COD/litre), through an equation of the Michaelis-Menten type.