Poultry manure is a significant source of nitrogen, but small amount of carbon needs to be added for faster degradation of organic matter in composting process. Composting of poultry manure mixed with wheat straw was carried out in specially designed reactors (32 L) under controlled laboratory conditions over 13 days. The aim of the study was to determine the influence of wheat straw addition to poultry manure on performance of composting process in terms of the following: the substrate temperature, carbon dioxide, ammonia, pH, electrical conductivity and organic matter. According to the results, the mixture of 83% poultry manure and 17% wheat straw (dw) among three different mixtures used in this research provided the best conditions for composting process. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.