An experiment related to biodiesel transesterification was successfully done. The chemical reaction of transesterification was conducted at 65 °C during 14 h of reaction time involving the ratio of methanol and used cooking oil was 70: 1. An additional catalyst is required upon 10 % of HPA (Heteropoly Acid) as an organic catalyst. The maximum conversion (yield) was achieved by 88.68 % with activation energy (Ea) was 53.99 kJ/mole with Pre-Exponential Factor (A) was obtained 2.9 x 107. Based on those experiments, s-curve modeling was designed. The s-curve was generated through three different selected temperature reactions as follows: 60, 65, and 70 °C (333, 338, and 343 K) with various reaction times 0.5, 1.0, and 2 h respectively. The mechanism to build the s-curve model through three stages starting by determination of reaction rate constant (k') through linear regression equation continued with the curve formation between ln k' with 1/T to produce a value of Ea and A. To produce the s-curve model was observed through numerical processes, interpreted and analyzed by applying the Avrami equation to determine reaction and temperature time is required by trans esterification reaction between methanol and used cooking oil. Referring to the curve was obtained several results which are the optimum temperature to obtain the best yield, time to obtain a 100 % yield, and time to obtain a determining yield. According to the s-curve model was formed, the time reaction 46.95 h and 22.79 h is able to achieve 100 % and 96.5 % of yield product by plotting reaction of temperature and time. This simulation can be applied to other biodiesel reaction which has different raw materials and types of a catalyst by keeping the same method to be applied through the transesterification method.