CAS 7783-06-4 · K-REACH · Republic of Korea

Hydrogen sulfide (H2S) under K-REACH

H2S · 硫化氢

Status: Registered. Hydrogen sulfide is registered under K-REACH. **On Korea TCCA Toxic Chemicals list** (verify against the current TCCA Toxic Chemicals list at https://www.nics.go.kr/ and NICS toxic-chemical database before relying; H2S's Acute Tox. 2 inhalation + Flam. Gas 1A profile triggers TCCA scheduling at industrial-grade). NOT on Korean Drug Management Act precursor list. NO active Korean AD/CVD case on Chinese-origin hydrogen sulfide currently (merchant cargo is rare globally; H2S captive intermediate). Korea has substantial domestic H2S captive intermediate at refinery + petrochemical Claus-process operations (SK Innovation, GS Caltex, S-OIL, Hyundai Oilbank, Lotte Chemical). KCFTA preferential zero-duty applies for any rare Chinese-origin imports.

K-REACH treats hydrogen sulfide as a **TCCA Toxic Chemicals scheduled substance** (TCCA Toxic Chemicals Handling Permit at destination facility, parallel layer to K-REACH chemical registration). Korea structurally domestic-supplied (SK Innovation + GS Caltex + S-OIL + Hyundai Oilbank + Lotte Chemical refinery Claus-process captive). **Hydrogen sulfide distinguishing pattern across all 5 regimes**: Sour-gas natural occurrence + refinery / petrochemical / pulp-mill / sewage-treatment by-product; commercial merchant H2S is rare (captive feed to Claus-process sulfur recovery batch 80 dominates) + completes sulfur chain alongside elemental sulfur batch 80 + H2SO4 batch 2 (H2S → S → SO2 → SO3 → H2SO4 Claus-then-contact chain) + chemical synthesis intermediate (mercaptans + thiophenes + sulfides + CS2 captive) plus heavy-water D2O production (Girdler sulfide GS process, declining) plus pulp-mill Kraft chemistry by-product downstream chains + high hazard profile across regimes (Acute Tox. 2 inhalation + Flam. Gas 1A + Press. Gas + Aquatic Acute 1; UN 1053 Class 2.3 + 2.1) + US OSHA PEL 20 ppm ceiling + 50 ppm peak Table Z-2 + NIOSH REL 10 ppm ceiling + EPA RMP 10,000 lb + EPA Clean Air Act Section 112 HAP + China Catalog of Hazardous Chemicals AND Highly Toxic Chemicals (Public Security Bureau supervision) + Australian SUSMP Schedule 7 dangerous poison + Korean TCCA Toxic Chemicals list.

Listing and threshold

Substance Hydrogen sulfide (H2S) (CAS 7783-06-4), H2S
Regime Korea Act on the Registration and Evaluation of Chemicals (Act No. 11789, "K-REACH" amended 2018)
Jurisdiction Republic of Korea
Status Registered
Tonnage threshold K-REACH registration required for existing chemicals manufactured or imported >1 tonne/year (verified per Korean Ministry of Environment / NIER guidance, https://chemical.chemlinked.com/chempedia/k-reach; threshold for new substances was reduced from 0.1 t/y to 1 t/y effective 1 January 2025 per K-REACH 2025 amendment)

Classifications under this regime

  • Korean GHS classification: Acute Tox. 2 inhalation + Flam. Gas 1A + Press. Gas + Aquatic Acute 1
  • **On Korea TCCA Toxic Chemicals list** (verify against current TCCA list and NICS toxic-chemical database before relying)
  • NOT on Korean Drug Management Act precursor list
  • Korean Customs Service (KCS) HS code: 281110
  • IARC: Not classified

Restrictions and conditions of use

  • **TCCA Toxic Chemicals Handling Permit required at destination facility** (verify TCCA status against NICS database)
  • KOSHA MSDS in Korean required at workplace (Acute Tox. 2 inhalation + Flam. Gas 1A hazard profile)
  • NO active Korean AD/CVD case on Chinese hydrogen sulfide currently
  • KCFTA preferential zero-duty applies (HS 281110)

Importer obligations

Korean importer of record must hold K-REACH registration AND TCCA Toxic Chemicals Handling Permit at destination facility. Korea has substantial domestic H2S captive intermediate at refinery + petrochemical Claus-process operations (SK Innovation + GS Caltex + S-OIL + Hyundai Oilbank + Lotte Chemical); merchant cargo rare globally.

Required documents

  • K-REACH registration number on Korean side
  • Korean MSDS (Acute Tox. 2 inhalation + Flam. Gas 1A hazard profile)
  • KCS declaration with HS 281110
  • China-Korea FTA Form CO
  • **TCCA Toxic Chemicals Handling Permit** at destination facility

Common compliance traps

The pitfalls that have bitten importers on this lane in the past. None of these is theoretical.

  • Korea has substantial domestic H2S captive intermediate (refinery Claus-process)
  • KCFTA preferential zero-duty applies
  • NO active Korean AD/CVD case
  • **On TCCA Toxic Chemicals list (TCCA Toxic Chemicals Handling Permit at destination)**
  • Major Korean captive sources: SK Innovation + GS Caltex + S-OIL + Hyundai Oilbank + Lotte Chemical

Where to read next

For substance-level identifiers (formula, molecular weight, SMILES, InChIKey), GHS hazard profile, IMDG transport class, and full sourcing reference for hydrogen sulfide (h2s), see the CAS 7783-06-4 sourcing reference.

For grade-by-grade buying notes, freight maths, supplier-tier pricing, and a worked landed-cost example, the hydrogen sulfide (h2s) cornerstone hub covers the full sourcing chain.

For the structure and history of K-REACH, see the K-REACH glossary entry.

Need cross-jurisdiction compliance support on this substance? Run it through the REACH / TSCA / IECSC / AICIS / K-REACH checker, or send us the substance and the destination and we will quote FOB China and CIF / DDP landed including the regulatory work on the destination side.

Read next

Cross-jurisdiction profile and sourcing references

Referenced in

5 pages across the Sourzi moat

This term shows up in 4 regulatory pages, 1 CAS profiles. Sample backlinks per content type below.

Regulatory (4)

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CAS (1)

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