Background and purpose: Hexahydrocannabinol (HHC) is a novel psychoactive substance that has gained attention due to its psychotropic effects and temporary legal status. It is widely abused in several EU and US countries, where it serves as a legal and easily accessible alternative to ∆⁹-tetrahydrocannabinol (∆⁹-THC). Despite its widespread use, few studies have examined its in vivo effects and safety profile. Experimental approach: This study investigated the pharmacokinetics, systemic toxicity, and acute behavioural effects of HHC in male Wistar rats. A mixture of (9R)-HHC and (9S)-HHC epimers (in a 1:1 ratio) was administered via intragastric gavage at doses of 1, 5, and 10 mg/kg. Behavioural effects were assessed using the Open field test and the Prepulse inhibition of acoustic startle response. Key results: Two hours after 10 mg/kg administration, concentrations of both HHC epimers peaked in blood serum and brain tissue. According to the OECD 423 toxicity test, HHC was classified as a Category 4 substance, with an estimated lethal dose of 1000 mg/kg. Compared to the control group (administered sunflower oil), the highest dose (10 mg/kg) led to reduced locomotor activity, increased anxiety, and impaired sensorimotor gating. Conclusions & Implications: HHC readily crosses the blood-brain barrier, exhibits mild toxicity, and produces behavioural effects similar to THC-like cannabinoids.