Cofiring tests were conducted in a boiler at the Hawaiian Commercial & Sugar factory at Putmene, Hawaii. Three tests were conducted; a baseline test firing coal and fuel oil (Test 1) and two cofiring tests utilizing coal, fuel oil, and biomass. In the latter two tests, bagasse (Test 2) and a blend of bagasse and fiber cane (Test 3) were used as the biomass fuel. Biomass accounted for 62% and 50% of the total energy inputs for Tests 2 and 3, respectively. All three tests were conducted in a spreader stoker-type boiler operating at a steam flow rate of 46.5 tonne h(-1) at 63.2 bar and 400 degrees C. Fuel properties, boiler efficiency, solids removed in the pollution control devices, and stack emissions of criteria pollutants were monitored during the test campaign and results are reported herein. In addition, a laser induced breakdown spectroscopy probe and a deposition probe were installed near the superheaters to characterize fire-side ash behavior under each of the test conditions. (c) 2006 Elsevier Ltd. All rights reserved.