香茅醛（Citronellal），学名3,7-二甲基-6-辛烯醛，是一种无环单萜醛。

无色透明液体。具有花椒香味。易溶于乙醇；乙醚；氯仿，微溶于水。有光学异构体。

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 is a major isolate in distilled oils from the plants Cymbopogon, lemon-scented gum, and lemon-scented teatree. The (–)-(S)-enantiomer of citronellal makes up up to 80% of the leaf oil from kaffir lime leaves and is the compound responsible for its characteristic aroma.