Methylchloroisothiazolinone/methylisothiazolinone
What is Methylchloroisothiazolinone/methylisothiazolinone?
Methylchloroisothiazolinone/methylisothiazolinone (CAS 55965-84-9), commonly identified as CMIT/MIT, is a broad-spectrum biocide active against bacteria, fungi, and algae. Also marketed as Kathon WT and Kathon 886; the active ingredient in Proclin preservative blends.
Where is Methylchloroisothiazolinone/methylisothiazolinone used?
- Water treatment and cooling tower systems: controls microbial growth causing biofouling, corrosion, and process inefficiency
- Oilfield and gas operations: injection biocide suppressing sulfate-reducing bacteria in produced water and pipeline systems
- Pulp and paper mills: applied to process water and slurries to prevent slime formation
- Rinse-off personal care and industrial coatings: in-can and in-process preservative
- Procurement teams source it primarily as a formulated aqueous concentrate.
Good to know: Grades vary by intended application, with formulations differentiated by the CMIT-to-MIT ratio and the presence of stabilizing salts.
Regulatory status
- The mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in a 3:1 ratio is assigned Index number 613-167-00-5.
Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.
Other Names (Synonyms)
Kathon WT|Kathon 886|Active Ingredient in Proclin|5-chloro-2-methyl-isothiazol-3-one;2-methylisothiazol-3-one|5-chloro-2-methyl-4-isothiazolin-3-one;2-methyl-4-isothiazolin-3-one|5-Chloro-2-methyl-3(2H)-isothiazolone with 2-methyl-3(2H)-isothiazolone|5-chloro-2-methyl-3-isothiazolone;2-methyl-3-isothiazolone|5-chloro-2-methyl-1,2-thiazol-3-one;2-methyl-1,2-thiazol-3-one|CMIT/MIT