The rate of hydrolysis of 1,3,5-tris(2-hydroxyethyl)hexahydro-s-triazine (triazine, 1) was shown to be strongly dependent on the pH of the aqueous solution: d[triazine]/dt = 2.6 x 10(-5)[triazine] + 2.2 x 10(6)[triazine][H+] at 22 degreesC; d[triazine]/dt = 4.8 x 10(-4)[triazine] + 3.5 x 10(8)[triazine][H+] at 60 degreesC. Furthermore, we have established the structures of the products from the reaction of triazine with S2-/HS- to be 3,5-bis(2-hydroxyethyl)hexahydro-1,3,5-thiadiazine ("thiadiazine", 2) and 5-(2-hydroxyethyl)hexahydro-1,3,5-dithiazine ("dithiazine", 3) by IR and I MR spectroscopy together with combustion analyses. 3 was not hydrolyzed and did not react with S-2/HS- at pH from 10 to 2.