A study was undertaken to optimize the use of the Hosoya system in composting poultry manure in a typical layer poultry farm in Greece. The farm is located about 50 km north of Athens with a Hosoya system installed which has been in operation for more than 4 years. During the study the performance of the system was investigated and samples of the material under process were taken for moisture determination and total and volatile solids analyses. The temperature of the material, as well as the temperature and the relative humidity of the surrounding air, were also monitored. The results showed that the composting process could not bet completed:in the oval Hosoya installation. This could be attributed to the required intensive daily turning and pushing of the manure in the installation, in order to reach the exit at the desired rate. As a result, an early drastic temperature drop of the material occurred. A further step is then necessary for efficient completion of the composting process of this type of manure. In such a case, the Hosoya system can be considered as the necessary mechanical precomposting step required for the high moisture and muddy-textured layer poultry manure prior to its being fully composted in piles or windrows.