This study aims to produce terpineol from alpha-pinene by direct one-stage hydration reaction mechanism. The study was focused to investigate the influence of organic acids and mixture acid catalyst between organic acid and phosphoric acid. Based on the experimental results and depending on the acid strength and affinity of catalyst to the carbocation mechanism, p-toluensulfonic acid was shown to have a better result compared to acetic and formic acid. The presence of phosphoric acid could boost the performance of acetic acid in term of acidity strength that increased the conversion of the reaction. The highest yield of terpineol from alpha-pinene in this hydration reaction in this study was 53.5 wt% using mixed phosphoric and acetic acid. Graphical Abstract [GRAPHICS] .