The moisture and ash contents of the feed material were determined according to the European Standards for solid biofuels (EN 14774 and EN 14775) [17]. The volatile matter was determined by the method of ISO standard (ISO 17246) [18], and the fixed carbon was calculated by the difference. The chemical composition of the feed material was analyzed according to the van Soest procedure [19], and the chlorine content was measured by bomb decomposition followed by determination of chloride with an ion selective electrode following the ASTM D 4208 method. TGA (Thermogravimetric analysis) of the ACQ-treated wood was performed with a thermogravimetric analyzer (TGA Q50, TA Instruments) under a nitrogen atmosphere (purge gas flow: 100 mL/min) at various heating rates (5, 10 and 20 °C/min). The sample weight used in each experiment ranged from 10 to 20 mg.