The non-catalytic synthesis of biodiesel in supercritical methanol from soybean oil was conducted in a batch reactor using three different reaction approaches: (1) process at constant temperature, (2) gradual heating process, and (3) process combining a phase of gradual heating followed by a phase at constant temperature (hybrid process). In the conditions leading to the highest yields of biodiesel during the constant temperature and gradual heating processes (87.5 mol% at 320 degrees C and 83 mol% at a heating rate of 2.60 degrees C/min, respectively), a considerable degree of thermal decomposition of the biodiesel synthesized (16 and 10 wt.%, respectively) was observed. However, the use of a low heating rate (0.51 degrees C/min) and a subsequent maintenance time of 10 min at 320 degrees C during the hybrid process completely prevented the onset of thermal decomposition reactions while transforming all glycerides into biodiesel, thus resulting in a yield of biodiesel of 99.9 mol%. (C) 2016 Elsevier B.V. All rights reserved.