Epoxidation of monoterpenes, α-pinene, β-pinene, limonene, α-terpinene, and (R)-carvone was carried out by the in situ production of a peroxyacid rather than direct addition of such an expensive and difficult to handle chemical.Previous reports showed use of metal catalysts with high yields, while methodologies without catalysts at high temperature showed yields lower than 30%.The authors report a methodology that produces peroxyacetic acid in situ yielding up to 75% pure epoxide at room temperature avoiding the use of catalysts.The products were analyzed by gas chromatography mass spectrometry (GC-MS), and structures were characterized by 1 H and 13 C nuclear magnetic resonance (NMR).