The in-situ chemical oxidation agents market is projected to grow from USD 677.0 million in 2026 to USD 1,632.4 million by 2036, at a CAGR of 9.2%. Hydrogen Peroxide or Fenton’s Reagents will dominate with a 32.0% market share, while petroleum hydrocarbons (btex, tph) will lead the target contaminant type segment with a 34.0% share.