Molekula
Osmium tetroxide
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 2000 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Osmium tetroxide is a highly toxic, volatile inorganic compound used primarily as a stain in electron microscopy to enhance contrast in biological samples, as well as a catalyst in organic synthesis. It is a powerful oxidizing agent with a distinctive pungent odor. CAS 20816-12-0, molecular formula OsO4, molecular weight 254.23 g/mol. Must be stored between 2–8°C in a tightly sealed, airtight container under inert gas. Signal word: Danger. Molekula supplies osmium tetroxide from research to bulk quantities with full documentation and ISO 9001:2015 traceability.
Example image for illustration only. Other packaging and pack sizes are available.
Pricing & pack sizes
These pack sizes aren't a limit. Molekula manufactures, sources and repacks to order — if you need 500 kg and only see 1 kg listed, . We quote from grams to multi-tonne.
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2 g — £1,451.00 per pack ex VAT · £1,741.20 inc. VAT
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Specifications
| Property | Value |
|---|---|
| Appearance | Yellow crystals |
| Melting Point | 40°C - 42°C |
| Heavy metals | ≤0.005% |
| Solubility | Passes test |
| Purity | ≥99.90% |
| Non-Volatile Matter | ≤0.2% |
| Ruthenium (Ru) | ≤0.01% |
| Osmium (Os) | 74.2 - 75.4% |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | 2 to 8 °C |
| Transport Class | 6.1 |
| Packing Group | I |
| Acidity | Acid |
Literature values
Published physical properties of the substance, not batch specifications.
| Property | Value |
|---|---|
| Appearance | Pale yellow solid; monoclinic crystals |
| Odour | Acrid, chlorine-like odor |
| Melting Point | 42 °C |
| Boiling Point | 130 °C |
| Density | 4.9 (relative, water = 1) |
| Vapour Pressure | 1.5 kPa at 27 °C |
Source: PubChem CID 30318 (HSDB, ICSC)
Identification
| Property | Value |
|---|---|
| SKU | 90036146 |
| CAS Number | 20816-12-0 |
| IUPAC Name | tetraoxoosmium |
| EC Number | 244-058-7 |
| Molecular Formula | OsO4 |
| Molecular Weight | 254.23 |
| Exact Mass | 255.9411 |
| SMILES | O=[Os](=O)(=O)=O |
| InChIKey | VUVGYHUDAICLFK-UHFFFAOYSA-N |
| InChI | InChI=1S/4O.Os |
| PubChem CID | 30318 |
| UN Number | UN2471 |
| REACH Code | Y110 |
| TSCA Listed | Yes |
| HTS Code | 28439000 |
| Tariff Code | 2843909000 |
Safety & GHS
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Corrosive
GHS05
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Toxic
GHS06
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Serious Health Hazard
GHS08
Hazard statements
- H300 + H310 + H330 Fatal if swallowed, in contact with skin or if inhaled
- H314 (sub cat. 1B) Causes severe skin burns and eye damage
- H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled
Precautionary statements
- P260 Do not breathe dust/fume/gas/mist/vapours/spray
- P280 Wear protective gloves/protective clothing/eye protection/face protection
- P301+310 IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician
- P303+361 IF ON SKIN (or hair): Remove immediately all contaminated clothing. Rinse with water/shower
- P304+340 IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
Documents
Safety Data Sheets (SDS)
Available in English, French, German, Italian, Spanish.
Certificate of Analysis (CoA) by batch
Enter a lot or batch number to retrieve the CoA for that specific batch. We can generate one from spec data if no PDF is on file.
Synonyms
- Acid, Osmic
- Osmic acid
- Osmic acid anhydride
- Osmium oxide (OsO4), (T-4)-
- Osmium tetraoxide
- Osmium(VIII) oxide
- Perosmic acid anhydride
- Perosmic oxide
- RCRA waste number P087
- tetraoxoosmium
Frequently asked questions
What is osmium tetroxide (OsO₄) commonly used for?
Osmium tetroxide is primarily used as a high-contrast stain in electron microscopy for biological samples, as well as a catalyst in organic synthesis and an oxidizing agent in chemical reactions.
What is the chemical formula and molecular weight of osmium tetroxide?
The chemical formula is **OsO₄**, and the molecular weight is **254.23 g/mol**.
How should osmium tetroxide be stored?
Store osmium tetroxide at **2–8°C** in a tightly sealed, airtight container, preferably under an inert atmosphere or in a desiccator to prevent moisture exposure.
What purity grades of osmium tetroxide does Molekula supply?
Molekula supplies **high-purity osmium tetroxide** (typically ≥99.9% purity) suitable for analytical and research applications.
Can Molekula supply osmium tetroxide in bulk quantities?
Yes, Molekula can provide osmium tetroxide in bulk, with quantities and packaging tailored to your specific requirements—please contact us for details.
What documentation comes with an order of osmium tetroxide?
Each order includes a **Certificate of Analysis (CoA)**, **Material Safety Data Sheet (MSDS)**, and **batch-specific documentation** for traceability and compliance.
Ready to order or need a custom pack?
Tell us the product, grade, and quantity — Molekula usually responds within one working day with pricing and lead time.