In an ethanol-fed expanded-granular-sludge-blanket (EGSB) reactor at 33 degrees C, 80-90% of the sulphate load was removed at a rate of 4 g S/1 d, provided that at least 6 g chemical oxygen demand (COD) per g sulphate-sulphur was supplied. The reactor started up in a matter of days. Gradually decreasing the ethanol to sulphate ratio (R) to about stoichiometry, resulted in 60-70% sulphate removal at rates of 7 g S/1 d. Similar tendencies were observed with ethylene glycol as sole carbon and energy source. Total COD removal never reached more than 70-75%. This was related to a rather high biomass washout. The sulphate removal efficiency decrease when R was set at levels below 6, apparently because sulphate reducing bacteria (SRB) could not compete with methane producing bacteria (MPB) for acetate produced from the substrate dosed. Thermophilic operation at 55 degrees C, after a stepwise increase in the reactor temperature over a period of 23 days, did not favour acetotrophic sulphate reduction. Yet, operation at 48 degrees C and subsequently returning the temperature to 33 degrees C clearly enhanced acetate conversion by SRB. In the case of an electron donor price of 0.035-0.075 USD/kg COD, the cost for operation at R = 6 was found to be competitive to that at stoichiometry, i.e. R = 2, provided the biogas produced was effectively used.