The liquid superficial upflow velocity (V-up) and hydraulic retention time (HRT) on the thermophilic treatment of oleate in expanded granular sludge bed (EGSB) reactors were investigated. The highest methane conversion rate of oleate, 93 mg CH4-COD/g VSS.d, was attained in a reactor operating at a V-up of 1 m/h and an HRT of 24 h. The typical EGSB reactor hydrodynamics (V-up>4 m/h and HRT<10 h) inhibited the treatment performance, mainly due to biomass washout in particulate form.