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U.S. exports of hfo-1234yf, hfo-1234ze, and hfo-1336mzz (HS 290351) totaled $33.6M in July 2026.
Importers of HFO-1234yf, HFO-1234ze, and HFO-1336mzz paid $446K in duties in July 2026 — an effective duty rate of 4.0% on $11.2M in dutiable value, based on actual customs collections rather than the published tariff schedule. HFO-1234yf, HFO-1234ze, and HFO-1336mzz imports of $12.0M in July 2026 ran 75% above the year-to-date monthly average of $6.9M.
Last updated: July 2026 dataHydrofluoroolefins (HFOs) represent the next-generation refrigerant technology designed to replace high-GWP HFCs in automotive air conditioning, commercial refrigeration, and foam-blowing applications. HFO-1234yf has become the mandated refrigerant for new passenger vehicle AC systems in the US and EU, driving substantial import demand. China leads US supply under tariff line 2903511000, with Mexico and South Korea as significant secondary sources. These compounds are unsaturated and chemically distinct from HFCs, giving them dramatically lower global warming potentials, which is why they are classified separately under heading 2903.51 rather than with saturated HFCs.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
51 shipments/mo
HFOs contain a carbon-carbon double bond, making them unsaturated fluorinated derivatives, while HFCs are fully saturated. The HS nomenclature separates saturated and unsaturated halogenated hydrocarbons, placing HFOs in heading 2903.51 and saturated HFCs in earlier subheadings. This chemical distinction also underlies their much lower atmospheric lifetimes and GWP values.
China is the dominant import source, which creates concentration risk, particularly given Section 301 tariff exposure on Chinese-origin chemical imports. Automotive OEM supply chains have tight specification and continuity requirements, so importers should assess alternative sources in South Korea and Mexico and maintain safety stock to buffer against trade-policy or logistics disruptions.
HSChapter 29
Subheading 1 of 41 in heading 2903
Subheading 290351 · $12.0M of $60.3M
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HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share | Duty Collected |
|---|---|---|---|---|---|
| 2903511000 | Hfo-1234yf, Hfo-1234ze and Hfo-1336mzz | $12.0M | 3.72% | 93.16% | $446K |
HS10 export codes under this HS6 parent, each with its own page. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 2903511000 | Hfo-1234yf, Hfo-1234ze and Hfo-1336mzz | $33.6M |
Import lines come from the U.S. Harmonized Tariff Schedule and export lines from Schedule B. The two are numbered by different agencies, so the same 10-digit code can appear in both tables describing a different product.
ImportsExports
Imports
$12.0MYoY · Pro
Exports
$33.6MYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.
Exports · July 2026
destination
Netherlands and Mexico together take 59% of it.
customs district
origin
entry
rate provision · imports
6.8% enters free of duty; the effective duty rate is 3.72%.