•A novel cannabinoid (epicannabidiol hydrate) was identified in hemp products.•Isolation and purification was successfully achieved by flash chromatography.•Analysis by LC/Q-TOF-MS and NMR verified the chemical structure.•α-terpineol is involved in the generation of this new cannabinoid. A novel and major cannabinoid (epicannabidiol hydrate) present in hemp plants and oils was isolated and characterized by a combination of flash chromatography and liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS). This novel cannabinoid differs from cannabidiol (CBD) by the absence of a double bond in the terpene ring and the presence of an additional hydroxyl group in the same terpene ring. The isolation procedure involved the use of normal phase chromatography with a silica gel preparative column, followed by reversed phase chromatography with a C18 preparative column. In this way, other major cannabinoids present in the samples, such as cannabidiol and Δ9-tetrahydrocannabinol, were separated and the focus was placed on the novel cannabinoid compound. Exact accurate masses were obtained for the compound of interest at m/z = 333.2424 in positive ion mode and m/z = 331.2279 in negative ion mode. Additional MS-MS analysis in negative ion mode revealed the position of the additional hydroxyl group in the molecule. Finally, the structural characterization was corroborated with 1H NMR and 13C NMR analysis, thus verifying the exact chemical structure of this novel cannabinoid, which has not previously been reported in hemp samples. Display omitted