Abstract: Four leaf litter types belonging to mediterranean tree species (sweet chestnut, Castanea sativa; downy oak, Quercus pubescens; holm oak, Quercus ilex and Aleppo pine, Pinus halepensis) were incubated in microcosms for 16 weeks. Five treatments were compared: three soaking periods 1, 6 and 24 h before incubation at 22�C and two different temperatures 18�C and 26�C with soaking for 24 h. Samples were collected after 2, 4, 8 and 16 weeks and the remaining dry weight measured. After 4 months, the litter had lost between 7 and 44% of its original mass. Litter mass loss of sweet chestnut was the highest, whereas that of Aleppo pine was the lowest and the 2 oak species were intermediate. Regression lines fitted to the data showed that for the species under study, litter mass loss was a single exponential function of time. Initial water imbibition had little or no effect on the litter mass loss and decomposition rate. On the contrary, temperature affected litter mass loss and decomposition rate, which varied between the plant species.