The corrosion behavior of various commercial alloys in sub- and super-critical water including extraction from the fly ash of an incinerated municipal solid waste ([Cl]=2800mg/L) between 473 K/saturated vapor pressure and 873 K/25 MPa. Though the corrosion problems for Ni-base alloys were the crevice corrosion and stress corrosion cracking near the critical point (between 623 K/saturated vapor pressure and 723 K/25 MPa), they were the metal loss at 873 K/25 MPa. Stress corrosion cracking did not occur on Ti. Though the corrosion-scale growth rate on Ti was smaller than that of UNS N06625 (Alloy 625) in the solution including extraction from the fly ash of an incinerated municipal solid waste at 873 K/25 MPa, it was rather larger in pure water at 873 K/25 MPa. Though UNS S31603 (Type 316L SS) and S32900 (Type 329 SS) showed smaller corrosion rate than N06625 at 873 K/25 MPa, they generated the stress corrosion cracking at 723 K/25 MPa and 873 K/25 MPa.