According to the differences in components, three representative components (plastic, kitchen garbage and wood) in municipal solid waste (MSW) were pyrolyzed in a fixed bed reactor to evaluate the influence of particle size on pyrolysis performance of single-component municipal solid waste (MSW). The bed temperature was set at 800 degrees C and each sample was separated into three different size fractions (0-5 mm, 5-10 mm and 10-20 mm). The results show for all the samples particle size has an effect on pyrolysis product yields and composition: smaller article size results in higher gas yield with less tar and char; the decrease of particle size can increase H(2) and CO contents of gas, as well as the ash and carbon element contents in the char. And the influence is the much more significant for sample with higher fixed carbon and ash contents, such as kitchen garbage, and less for sample with higher volatile content, plastic in the test. Crown Copyright (C) 2009 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu. All rights reserved.