The sludge from cellulose treatment plant is rich in organic matter (MO) and can be used to improve the chemical and physical properties of the soil. The aim of this study was to evaluate the effect of the application of sludge from cellulose wastewater treatment plant on the physical and chemical properties of volcanic soils (series Gorbea and Collipulli). There was added sludge (0, 10, 20, 30 and 50 Mg ha-1) to the soils and were incubated for 75 days at 22 ± 2ºC. At 15 and 75 days the content of organic matter (MO), available nitrogen (N), pH, extractable Al, field capacity, bulk density and aggregate stability was determinated. The application of sludge improved significantly (p ≤ 0.05) the levels of nitrogen and organic matter in both soils, as well as the pH, with the consistent decrease of Al level. On the other hand, the different doses of sludge did not improve significantly the physical properties of the soils, with the exception of the stability of the aggregates in the soil series Gorbea. The minor effect in the physical properties could happen due to the fact that the period of incubation (75 days) was not sufficient to provoke significant changes in the physical properties of the soils.