Alkenes are very important moieties in Organic Chemistry and have been employed as starting materials for important syntheses of organic compounds. In this review, we present organocatalytic reactions, where an alkene plays the central role, especially their organocatalytic oxidation to epoxides. This topic plays a pivotal role in our recent research, utilizing H2O2 as the green oxidant and a ketone as the catalyst. Extension to other oxidative transformations is also presented.