Fuel synthesis from natural rubber mixed with tapioca starch has been studied in a batch reactor of 250 ml capacity at a rubber:starch ratio range 8:2-10:0, temperature 325-400 ํC, carbondioxide pressure 020 bar and reaction time 30-60 min. The process variables were rubber:starch ratio, temperature, carbondioxide pressure and reaction time. The process was carried out by two-level factorial experimental design method. The result indicated that rubber:starch ratio and temperature have a significant effect on gas, solid and liquid yield. The liquid yield reached 86.86% at optimum condition of rubber:starch ratio 9:1, temperature 350 ํC, carbondioxide 0 bar and reaction time 30 min. In term of oil yield, it showed that there was a synergism between rubber and starch. Analysis of liquid properties was found that the main composition of oil was saturated hydrocarbon. The addition of starch in reactant, it also found oxygen group in structure of saturated and aromatic hydrocarbon molecule. Synthesis liquid had heating value as high as petroleum crude oil.