Many proteins produced in E. coli accumulate in inclusion bodies. This study aims to detect the role of temperature in reducing the formation of inclusion bodies during recombinant human prethrombin-2expressed in E. coli BL21 (DE3) Arctic Express host. In this study, we created a host growth curve to find out the right time to add an inducer. The inducer used in our experiment was IPTG 0.1 mM. The fermentation process use a temperature of 12°C and 22°C. The results showed that recombinant human prethrombin-2 was successfully expressed as protein soluble using an optimum temperature of 12°C in E. coli BL21 (DE3) Arctic Express. It was indicated from the 63kDa protein band obtained from the soluble fraction on SDS-PAGE. The higher temperature of fermentation increased the amount of protein in the insoluble fraction due. It concluded that the fermentation temperature affect the rate of prethrombin-2 expression.