Citronellal

What Citronellal smells like

Citronellal is a fresh, lemony-green aldehyde with the recognisable smell of citronella and a rosy side. Suppliers describe fresh, lemony, citronella-like, slightly green and rosy, and fresh, lemony, slightly floral and citronella-like with a mildly soapy, clean quality. A glossary places it between citral and citronellol — less piercing than citral, less rounded and sweet than citronellol — and notes a floral note closer to lily than rose as the sharp top evaporates. It is the main constituent of citronella and lemon eucalyptus oils.

Leading note

Lemony citronella

Clear facets

Green

Supporting facets

Rosy

Faint facets

Waxy aldehydic, lily-like floral

Character

Fresh, sharp, green, clean

• lemony
• citronella
• green
• fresh

What makes Citronellal distinctive

It is the citronella note itself — lemon pulled towards green and rose — which is why a trace makes a composition read 'citronella' rather than 'lemon'.

Concentration and dilution

Its sharp lemony top evaporates to reveal a softer floral note.

How Citronellal is used

Used for lemony-green freshness in functional fragrance and citrus colognes, and as a raw material for hydroxycitronellal and other fragrance chemicals.

Typical role: modifier (used in small amounts to change the character of a blend).

How Citronellal differs from similar materials

Citral*

One glossary describes citronellal as less piercing than citral; citral is the pure, sharp lemon, citronellal greener and rosier. (compared directly by a cited source)

Citronella Oil (Java)

Citronella oil adds geraniol's rosiness and grassy herbaceous notes to citronellal's lemony green.

Lemon Eucalyptus Oil

Lemon eucalyptus oil is mostly citronellal, with a softer, balsamic-floral drydown; citronellal alone is sharper and more linear.

Citronellyl Nitrile

The nitrile is a stable, harder lemon with a nitrile undertone; citronellal is fresher and rosier.

An asterisk marks a difference that a cited source states directly. The others compare the published descriptions of each material. Smell varies with grade, supplier and dilution; compare them side by side on blotters before substituting one for another.

Formulation considerations

Subject to an IFRA Standard; check the current limits for the product category. Unstable in some bases.

Identity and classification

Type

Aroma chemical

Origin

Occurs in nature

Odour family

Citrus / Green

Note position

Top note

Physical form at room temperature

Liquid

CAS number

106-23-0

Molecular formula

C10H18O

Molecular weight

154.25 g/mol

IUPAC name

3,7-dimethyloct-6-enal

The CAS number, formula and molecular weight are taken from PubChem compound 7794, whose own record lists this CAS number; checked 19 October 2026.

Safety and compliance

The IFRA Standards Library lists a Standard covering Citronellal:

• "Citronellal" — Restriction, 49th Amendment, published 2020-01

Limits differ by product category and are set out in the Standard itself; this page does not reproduce them. The list above reflects the library as read on 19 October 2026.

Hazard classification of the neat substance, as PubChem summarises it, read 26 October 2026. Companies notifying the ECHA C&L Inventory classify it (2,050 reports): H319 causes serious eye irritation (99.4% of reports); H317 may cause an allergic skin reaction (97.5% of reports); H411 toxic to aquatic life with long lasting effects (77.9% of reports). 1 of the reports find it does not meet the hazard criteria. A skin sensitiser classification concerns handling the neat material and the dose in a finished product; the IFRA Standards, where they apply, set the limits. Unless it is harmonised, this is the notifiers' own classification, not a binding one.

This page is general information, not a safety assessment or a specification. Confirm identity, composition, IFRA status and allergen content from your supplier's documents for the lot you hold.

Materials it works with

• Citronellol

  Aroma chemical · Floral / Green — rosy, fresh, citrus, waxy

• Citronella Oil (Java)

  Essential oil · Citrus / Green — lemony, rosy, grassy, fresh

• Geraniol

  Aroma chemical · Floral / Citrus — rosy, sweet, citrus, fresh

Citronellal is also suggested as a partner on the pages for Lemon Eucalyptus Oil and Melissa Oil.

Used in formulas and accords

Used in 3 published formulas

Citronellal is an ingredient in 1 perfume formula, 1 accord and 1 base in the Formula & Accord Library.

Community formulas

• Finger Lime Accord

  Community Formula · Accord · listed as “Citronellal (CAS: 106-23-0)”

• Fougere Base

  Community Formula · Base · listed as “Citronellal 1%”, at 1%

RUŌOD House Originals

Original compositions by RUŌOD House.

• Magnolia Cartography

  RUŌOD House Original

Further reading

• Citrus Oils in Perfumery: Bergamot, Lemon, Orange and Their Limits

  The main citrus oils, phototoxicity and FCF bergamot, why citrus fades and how to extend it, oxidation, allergens, and grades from expressed to terpeneless.

Questions about Citronellal

Sources

• PubChem — compound 7794, checked 19 October 2026.
• PubChem — GHS classification (the ECHA C&L Inventory notifications and any harmonised EU entry), read 26 October 2026.
• IFRA — Standards Library, read 19 October 2026.
• Scentspiracy — Citronellal — distributor's description.
• Premiere Peau — Citronellal — published perfumery reference.
• The Good Scents Company — citronella odour category — odour database.
• Olfactory profile: the RUŌOD Lab team's synthesis of the published descriptions above, reviewed 20 October 2026. Evidence: more than one published description. Classification and the short description: revision 1. Descriptions of odour are judgement, not measurement.