This study presents the feasibility of converting a non-edible oil source native to the Africa region - croton megalocarpus oil to methyl esters (biodiesel) using sulfated tin oxide enhanced with SiO(2) (SO(4)(2-)/SnO(2)-SiO(2)) as super acid solid catalyst. This study was conducted using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (alpha) = 2. The reaction parameters studied are reaction temperature (60-180 degrees C), reaction period (1-3 h) and methanol to oil ratio (1 6-1.24) Although the oil was found to contain high free fatty acid, however, yield up to 95% was obtained without any pre-treatment step with the following reaction conditions: 180 degrees C, 2 h and 15.1 methanol to oil molar ratio, while keeping constant catalyst concentration and stirring speed at 3 wt % and 350-360 rpm, respectively (C) 2010 Elsevier Ltd. All rights reserved.