Citronellal or rhodinal or 3,7-dimethyloct-6-en-1-al (C10H18O) is a monoterpenoid, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent.
Citronellal has insect repellent properties, and research shows high repellent effectiveness against mosquitoes. Research shows that citronellal has strong antifungal qualities.