Pretreatment of pre-blended palm and rubber seed oil (50:50) was studied. A parametric study to determine the effect of alcohol-to-oil ratio, catalyst loading and reaction temperature on free fatty acid (FFA) content was also conducted. Interestingly, the FFA percentage of pre-blended feedstock has been reduced significantly from 20 to below 2. The optimum value for the reduction of FFA was found to be 1.5 wt. catalyst, alcohol-to- oil ratio 6:1, 62 °C reaction temperature at constant stirring speed (400 rpm) and reaction time 1.5 hours. NaOH/bentonite was also investigated and characterized as a solid heterogeneous catalyst for transesterification. The characterization was conducted by FTIR and XRD analysis. The catalyst showed good results by producing 92 wt fatty acid methyl esters at reaction temperature of 62 °C and reaction time of 3 hours. © 2016 The Authors.