We studied in batch reactors the kinetics and characterization of 70 degrees C, volatile fatty acids (VFAs)-grown, upflow anaerobic sludge blanket granular sludge with 55 and 35 degrees C sludge as reference. The half-saturation constant (K-s), the inhibition constant (K-i), the maximum specific methane production rate (mu(CH4max)), and the inhibition response coefficient (n) of the 70 degrees C sludge were 6.15 mM, 48.2 mM, 0.132 h(-1), and 2.48, respectively, while no inhibition occurred at 55 and 35 degrees C, where the K-s was 3.67 and 3.82 mM, respectively. At 70 degrees C,the highest initial specific methanogenic activity (ISMA, 0.311 gCH(4)-COD per gram volatile solids per day) on VFAs was about 12-15% lower than that on acetate and three to four times less than the ISMA for the 55 and 35 degrees C sludge. In the acetate conversion study, residual acetate (79 mg l(-1)) at 70 degrees C was three to live times higher than that at 55 and 35 degrees C. Further, the methane produced as percentage of the acetate consumed at 70 degrees C (89%) was lower than that at 55 (95%) and 35 degrees C (97%). At 70 degrees C, 10% of the ISMA remained after 15 days of starvation as compared to 26% (55 degrees C) and 92% (35 degrees C) after 30 days of starvation. Thus, the kinetics of the 70 degrees C granular sludge seem to differ from those at 55 and 35 degrees C.