The use of wooden crates for composting a mixture of 70% grass, (Digitaria decumbens), and 30% coffee pulp, combined with 2% Ca(OH)(2), was studied as a method for preparing substrate for the cultivation of Pleurotus ostreatus. Crate composting considerably modified the temperature pattern of the substrate in process, as compared to pile composting, where lower temperatures and less homogeneous distributions were observed. Biological efficiencies varied between 59.79% and 93% in the two harvests. Based on statistical analysis significant differences were observed between the treatments, composting times and in the interactions between these two factors. We concluded that it is possible to produce P. ostreatus on a lignocellulosic, non-composted, non-pasteurized substrate with an initial pH of 8.7, and that composting for two to three days improves the biological efficiency. (C) 2003 Elsevier Ltd. All rights reserved.