In this study, sea mango (Cerbera odollam) oil which is rich in free fatty acid was utilised as the feedstock in one-step superheated methanol vapour (SMV) transesterification reaction without going through pretreatment step. SMV transesterification reaction was initiated by injecting superheated methanol vapour into sea mango oil phase. Effect of methanol flow rate at the range of 1-4 mL/min as well as effect of reaction temperatures at the range of 260-290 degrees C was studied based on FAME production rates at constant initial oil volume of 100 mL. Kinetic modelling of semi-batch system, incorporating second-order of three-stepwise reversible transesterification of triglycerides (TG) and second order of reversible esterification of free fatty acid (FFA) were verified simultaneously using ordinary differential equation (ODE45) solver. It shows that transesterification reaction of TG and esterification of FFA would occur simultaneously. The high activation energy of 50 kJ/mol and low reaction rate constant of 1.62 x 10(-4) dm(3)/mol min verified that the reaction of TG to become diglycerides (DG) as the rate limiting step in this semi-batch SMV system. (C) 2015 Elsevier Ltd. All rights reserved.