A two-year demonstration run of a 500° C/9.8 MPa high-efficiency waste-to-energy (WTE) pilot plant has been started from February 1998. In this plant, SiC refractory tile, alloy 625 weld overlay and NiCrSiB alloy HVOF were applied on waterwall and ten kinds of conventional and newly developed solid-wall tubings, weld overlayed tubings, composite tubings and cermet spray coated tubings were tested in superheater. From the interim results after approximately 9400 hours operation, no remarkable waterwall corrosion was recognized, and corrosion rate of main superheater materials showed less than approximately 1 mm/year.